During the scripted encounter on the way to Odin, you can use Zombie on the Armadodos and then use X-Potions or Curaga spells to finish them off quickly. If you also cast Berserk on them, they won't be able use their Earthquake attack, which might save some more time. The Chimera on the other hand is vulnerable to Gravity damage and Slow, so if you use Demi and Slow, it should go down relatively fast.
As for getting Odin, there is no real recommended time, as he is just optional and no longer possesses the valuable Triple spell. If you try to beat him right after getting control of the Garden, it will likely be hard. But at that time, your party members can already have around 3500 HP and solid stats with the right levels and/or junctions. The spells you should have for junctions when trying to tackle him right away are as follows: Regen, Bio, Life, Meltdown, Reflect, Death, Haste and Stop. Pain is also useful if you managed to get a full stock during the NORG event, but is not a must. The most important thing is that you have something effective junctioned your Spirit stat and some AoE heal available.
Enter the sewers from Caraway's mansion and head east until you reach the ladder that leads to the boxes near the Presidential Residence. From there, go one screen to the left and wait there for several seconds until the Iguions "appear" (I would love to make them visible at that place, but due to Deling tool limitations, I can't).
For the scripted fight in Centra you can also use Full-Life on Armadodos after instantly killing them, the Chimera is also vulnerable to Vit 0 which the damage you deal to here quite a bit.
For Odin also recommended to have Stops junctionned to Statut Defense, I personnaly beat him with 2 characters under Shell, one was dealing damage with Double -aga spells the other was healing with Double Cura.
Also kinda cheap but for the all Centra thing you can use the Fast Forward option (F1 on Steam and whatever it is on Remaster), which speed up the game but doesn't speed up the timer. I also like doing Odin early cause he has a Luck-J Scroll to steal, which IIRC is the earliest way to get Luck Junction.
Anyway so I've been finally replaying the mod decide to not do an LP in the end, just recording the boss fight with the Lionheart Mod. Pretty much as good as I remember so far, a little more difficult but otherwise it's manageable.
I don't have much to add to Lionheart Mod I'd say however it started pretty similar to normal mod, I think the first fight I noticed the difference was during the Esthar Soldier fights on Laguna's Second Flashback, they didn't kill me but I definitly notice the increase damage compare to Normal, bosses after that were a little tougher than I remembered (most noticeably Brothers and the second fight with the tank in Horizon for me), Diablos was more challenging that what I remembered which is good.
Obviously the Hardest I got so far was the re-encounter with X-ATM092 at Dollet, but that's mainly cause I'm stubborn and wanted to do it before ending Disc 1, which of course means I was terribly underlevel for this fight, but manage to get it after some tries. And there is no much more to say about Disc 1, I'm trying to complete every sidequest compare to last time wher I was going full blind and miss a couple of new sidequests, I like the new optionnal fights.
Finally found these Iguions, maybe could add an hint that the player need to wait somewhere in Caraway's dialog, I thought I had to found some kind of trigger to analyse, so would have honnestly never guessed by myself, the Iguions fight was good think I was a little Underpower for it, but good fight that put Demis and Irvine's AP Ammo to use and the reward is nice.
As for overall balance between character :
-Squall is pretty good quite tanky, and once you get Elemental Attaque Junction unlock and Darkside he can deal some serious damage, his Limit is still quite powerfull to.
-Zell : His Duel can still deal serious damage, altough sadly I'm a bit rusted with him since I haven't played the game in a very long time, I need to derust myself and found my combos back as I forgot them, but he can truly be a beast if you master his Duel (which compare to Vanilla doesn't involve spamming Booya and Top Punch again and again as doing so will lead you nowhere). Early on I admit I just putted him on Berserk a couple of time for extra free damage, since he is terrible at magic.
-Selphie : Second best magic however I feel she outperform the other girls early, due to her Limit being honnestly busted for early game (I didn't want to rely on it tough so I avoid using it), and also having an higher Speed than Quistis or Rinoa which did make a difference on a couple of fights (the X-ATM092 refight notably).
-Quistis : Probably the most versatile character, Elemental Damage, AoE heals, Gravity damage, Mighty Guard, I love her, Blue Mage in general are my thing, tough early game she is not the best having the lowest Magic of the 3 girls and lacking Blue Magic early on.
-Rinoa : Highest Magic Stat, but slower than Selphie, her Angelo Limit are actually quite nice when you can afford to Junction to Str and Mag at the same time, her Angelo Canon is a pretty AoE in fact, I'm avoiding learning Awakening Moon tough, I think I had tackle it somewhere but I think this move is pointless and is more of a burden than anything else, and I don't see the point as if I want an AoE heal through a Limit Break I would much rather use Quistis's White Wind which is more reliable.
-Irvine : Hard to argue just how usefull he is, less Str than Squall or Zell but better speed, and his Limit Break is surprisingly versatile, Normal Shot works well for single target early on, Shotgun for AoE, Demolition Ammo for Crit Fishing, Dark Shot to shut down Mobs, AP Shot to bypass Defense, Irvine has always been my man in this game and it's not gonna change. He sadly can't truly shine as a Critical Damage Dealer early on due to not having access to Luck Junction.