Here's a thread made specifically for PetCo baby care! http://www.bettafish.com/showthread.php?t=457330
Wow, he looks exactly like how my boy Pierce looked like when I got him! The good thing about your fish is that s/he is larger than the normal babies they sell which are usually around .3-.5 of an inch. The bigger they are, generally the better off they will be in the end.
I can't say for sure with these pics but it looks like a young male DTPK which is what mine turned out to be. Here are two pics of Pierce to show you, first is when I first got him three months ago
Size comparison with a full grown HM male
And this was about a week ago.