it's probably a silly question but Im just curious when my bill will be coming
It depends when your billing cycle starts. Keep in mind you'll be billed from the day you activated until the end of your billing cycle PLUS 1 month in advance. This is proration so don't be surprised if your first bill is a little bit bigger. The only way to verify your billing cycle would be to login into your self serve account. In overview it will tell you when your next bill starts.