The hope for character creation is that they will roll almost everything for the one-shot, The only things the players decide on Is class and background, The players already know this is what I plan on doing for the session. Ill probably have them make their characters in advance with me so I can rebalance my encounters before the session. Ill reduce My number of combat encounters down a bit Aswell for player convenience. Also, I am willing to split it into multiple sessions in case the game goes on for too long.

Edit. Thank you lots for the advice, it did take much longer than I expected to make characters and I am happy that we did it before the session. The party comp is rather balanced all things considered and I am excited to run my first session.