Gwen, I count for myself at almost all of my meets. Basically, what Blake said. As soon as the cards get put out for the session, go over and see where you are at. Count all the 1st attempts. There will be some that will finish before you start, so go ahead and count those lifter's 2nd and 3rd attempts as well. Just go down the list and make assumptions about the 2nd and 3rd attempts to see where you will be, roughly. You won't get it exact. Do your warm-ups and periodically go up to the cards and check where they are on the platform to where you are in your warm-ups.
Best is if you can find another lifter with similar starting weights as you and just follow them, especially if they have a coach. Most will be more than happy to have you work in with them, and their coach may help you out too.