Just wait and do it right, a few weeks won't make a big difference.
Even though you're used to being in the water doesn't mean you shouldn't have your first scuba dive with a qualified instructor. Those folks spend a lot of time and money to get properly trained to take new divers out.
In the unlikely event that something does go wrong who would you rather have at your side, someone who is an average diver that decided it was okay to break the rules or a qualified instructor who has dealt with problems before?
Even though you're used to being in the water doesn't mean you shouldn't have your first scuba dive with a qualified instructor. Those folks spend a lot of time and money to get properly trained to take new divers out.
In the unlikely event that something does go wrong who would you rather have at your side, someone who is an average diver that decided it was okay to break the rules or a qualified instructor who has dealt with problems before?