My little seedlings are finally starting to split! I’m getting nervous about how to care for them now so any advice for this stage would be appreciated!

I started these seedlings from one of my plants back in May, and honestly I'm surprised they've lived this long 😅 I've gone from watering everyday to spritzing them every few days and watering when it feels too dry. Should I reduce it even more now that they're starting their first split? When should I worry about moving them to an even grittier substrate? (Sandy on top with a 50/50 mix of soil and perlite underneath)

I've come so far, I don't want to kill them all by making the next step wrong. Thanks in advance!