It is very good that you are going ahead with getting the cert.
But, I think there has been some misleading information posted in here that bears addressing.
Statements have been made like "you get longer NDLs and shorter surface intervals", and "you get more margin of safety".
That is all only sort of true.
If you use Nitrox and dive to your NDL, your surface interval is not any shorter than if you dived Air to your NDL. What IS true is if you dive Nitrox, but you stick to the NDL for Air (for the depth you're diving), THEN you get a shorter surface interval - but then you are not getting a longer NDL.
If you use Nitrox and dive to your NDL, you do not have any more margin for safety than if you dived air to your NDL.
Diving to your NDL (for the gas you're using and the depth you're diving) gives you the same surface interval and the same margin for safety, no matter what gas you're using (Air or any flavor of Nitrox).
What you CAN do that splits the difference is you CAN choose to use Nitrox and spend a little more time on the bottom, without going all the way to your NDL. Then you are getting more bottom time AND would have a shorter surface interval AND more margin of safety. For example: You could be diving to 60'. If you use air, your NDL would be 60 minutes. With Nitrox, it might be 80 minutes (just for the sake of discussion). If you use Nitrox, but only stay down for 70 minutes, then compared to using air and staying for 60 minutes, you got more bottom time, would have a shorter surface interval, and would have a greater margin of safety. But, if you used Nitrox and stayed for the full 80 minutes, then your surface interval and margin are just the same as if you had used air and stayed for 60 minutes.
This should be covered fully in your Nitrox class. Enjoy!!