OPK Help!

Hello, I started using OPKs around cycle day 10 as this is our first TTC cycle. According to glow this is week is my fertile week (December 7th - December 13th) and ovulation predicted around December 11th/12th. When would you expect to start seeing the OPKs becoming darker? They seem quiet consistent with being lighter at the moment. Some days slightly darker and I mean very slightly. I am testing temp using a bbt too. Also, does drinking too much and holding the strip too long in urine weaken the LH surge? Thank you 😊