Dive right in.

You did make her a promise. And she looks like she might die if she has to wait any longer. So, down come your trousers, and in you go.
As you thrust in, the ridiculous amount of lubrication making it easy despite how tight she is, she practically screams.
"Oh! Yes! Yes! Harder! Faster!" She yells, pushing her ass up in the air to accept you and starching at the floor with her hands. You start to thrust, and she meets you at every turn, eventually so enthusiastically that she pushes you back, so you fall on your ass. You slide out, and she whimpers, like you just kicked her.
Quickly, she turns and springs on you again, impaling herself on you and getting ready to ride you for all you're worth, her boobs bouncing happily, her tongue hanging out of her mouth and breathy moans coming thick and fast. She looks like she's in the brink. Come to mention it, so are you. She's been so frenzied... Just one question remains, where are you going to bust it?