FET after a freeze all

In January I had an ER because I took the Lupron trigger shot I had to do a freeze all. I got my period yesterday and my RE scheduled me to come in on day 3 of my period, which is tomorrow, for a baseline appointment. Once they get my labs back my RE said I'll start my estrogen patches and pills. I've never done this process before so I'm unsure of the timing. How long do you normally wait after your period to start the estrogen pills and patches?