You count from the first positive. You will probably ovulate some time between later tonight and tmrw night, but possibly the next day. You bd yesterday, so you are covered there, but I would definately try to bd today aswell. I get 2 days in a row of positive opks every cycle, so you can get more than one day of positives before the LH surge is done. It is pretty common to get 2 days in a row. Do you bbt temp at all? If you don't, it may be a good idea to start, so you can confirm ovulation.