I don't know all the rules. Both of us are from Orthodox backgrounds, "black hat" litvish. We went on 3 dates already and I was wondering if on the fourth I could give compliments. I know on earlier dates you're not supposed to but when does that end? Assumably to compliment her appearance would be inappropriate but would it be ok if I complimented something she was wearing or maybe even tell her that I think a certain mannerism of hers is cute, or would that too be out of place?
The answer I got was 5th-6th date, or about when the couple is ready to drop the shadchan. That's also the time you can start using her name directly. Of course, as mentioned above, everyone has their own guidelines and each should ask their own shadchan for what these guidelines are in their circles