Confused about QSBS eligibility - do I need C-corp from day one?

Real talk: i'm incorporating my SaaS startup and heard about Qualified Small Business Stock (QSBS) which lets you exclude up to $10 million in capital gains from taxes if you hold the stock for 5 years.

My lawyer is saying I need to form as a C-corp to qualify for QSBS. But I was planning to do an LLC with S-corp election because I heard that's better for taxes early on tbh.

Do I really need to be a C-corp from the beginning? Can I convert later and still get QSBS treatment? Trying to figure out if it's worth it.

This is all super helpful. Sounds like for any startup that might want to raise VC funding or have a significant exit, C-corp is the way to go from day one.

What about state taxes though? Does QSBS exclusion apply at the state level or just federal?