This has been discussed many times here.
The best option would be to speak to someone you trust like your Rebbe, Rav or parents if you feel they can help and are comfortable. This answer really depends on your personal story therefore it's really important to seek guidance.
In general, if your struggle is "standard" i.e. what the average bochur goes through, then make sure you have it under control but you shouldn't be telling a girl on a date any of this stuff (unless you are looking for a way out...).
In more severe cases, she will need to know at some point and finding the right time really needs guidance from an experienced mentor. Too early she might freak out, too late she might feel you breached her trust.
You need to know where you really stand, therefore it's important to seek guidance.
But really this is private, treat it like a medical condition. Imagine you had a condition that you wet your bed every night. Your wife is going to have to know before she finds out on her own or she wont be too happy On the other hand if you tell her on the first date she will run away (not because it's that scary just because it's weird). Someone with experience can guide this person in how to go about this.
Hatzlachah, may you find the right one quick. Just know that if you are here and working, you are worthy to be anyone's chossen.
