I think you'll be fine. Try holding off on the masturbation for a few days prior or cut down to just once a day. Some find that masturbation on a regular basis can sort of temporarily desensitize the head of the penis a bit. As this is where a LOT of your sensation is felt, it could impede things.
OK, that's the purely physical side. Now the rest.
Foreplay! You've heard about it, you've done it. But not like this!
Start the morning of or the day before and begin a slow build up of the feelings of love and connection which keep the clothes on. Such as treating her nicer than usual, taking her out to dinner, cuddling and saying nice loving things to her, etc... She will find this a great(if slow) turn on. Without realizing it so will you. on a level below your conscious mind, you will get really turned on. Then when you finally penetrate her you'll be so excited, things will just kind of happen automatically-you won't have to even think about it. Actually it's better if you aren't thinking about it as that by itself can prevent it.
When the time comes to take your clothes off in the evening, all that foreplay will have done it's work and you'll find things easier. Just start out with little things and as time passes increase the intensity of the niceness or intimacy.
There are many things women find intimate that us guys don't think of that way. If you learn to recognize these things, you can start foreplay when you awaken and finish with incredible sex in the evening when you are getting ready for bed.
Sound complicated? It's not. just spend the entire day showing her how much you love her while you both have your clothes on and when you do take them off, you'll be so hot for each other that you'd better have a fire extinguisher handy!