Who cares? If you go too fast the first time you have sex with her, just feed her some line about how "you're just so hot, omfg I can't take it baby" or something like that. Make her feel special, like it's never happened to you before. She'll appreciate it.
Then... after you cum super fast, make sure you give her something. Or just go down on her beforehand until she goes, then do your thing and if you go too fast, then afterwards finger her to orgasm, so she's gotten off at least twice. Then she won't mind.