OK,  all of you 20, 30 and even 40-something guys can skip this post.  

I'm a 50-something gentleman, and these days it takes a latex free oral session to get me off.  
I've been fortunate, and most ladies I just say, " oral is the only way for me to get off".  So far, no complaints, but I always feel like I'm hiding something and a bit guilty for having not said so in advance.  

Am I good to go, or should I let the lady know in advance, or before the festivities begin?  
I always strive to be a great date, and would like to know.  What is your preference?  

Thanks in advance

If you've read her reviews and know that oral is on the menu, it should not make a difference.  Personally it is my preferred method of finishing things  But regardless, it should not make a difference when during the session you mention it.