I guess that's mostly off topic here, but of course you can start at any block you like. Namecoin (the first auxpow chain) just started later (block 19'200 or so IIRC) because auxpow was developed only after launch. There are chains that support it from the start.
Thank you - will post in correct topic next time . Was wondering if it needed a certain amount to pass first for security reasons to ensure blockchain stability . Currently developing a auxpow coin however could not find notes specific to this topic