I would just like to point out that she has just as much responsibility to bring her best game to the table, & get you satisfied.
Patriachal sex is over - sex is a two way street, ensure she attends to your needs too! Do not get whipped on day one, or put her on a pedestal. You're just two kids embarking on a mutually rewarding adventure, & you both have responsibilty for each others needs, sharing a few giggles, & having a jolly good time.
PS - if you do come early - just keep going! At your age, this might not be a problem. I know that on my first time, I let loose after a minute, & kept on till number 2, 10 minutes later.
Frankly, the more you heavy pet first, before engaging in full on sex, days, or weeks later, the more comfortable & relaxed each of you should be - but we all know the pressure of just getting rid of the 1st time!