The petition just got created under an hour ago, and the signature counter probably doesn't update in real time.
It is still at 1 signature.
I signed, too, but I didn't see an update in the signature count either. According to https://www.buzzfeed.com/blakemontgomery/signatures-on-the-w... We the People is experiencing technical difficulties at present; the Trump administration said it was "a question of high volume."