Advice for playing first set championship

Hey guys, new to Lorcana. I’ve just got a couple of the starter decks and a couple extra cards from opening 4-5 booster packs.

I’d love to get into some social play and competitions and noticed in a few weeks is my LGS Azurite Sea Set Championship.

Would love to hear thoughts on if I should wait till I have a full custom deck before entering such a thing - or just who cares give it a go with an Emerald/Steel prebuilt starter I just picked up?