Why can't they prescribe me Clomid now?

Kimberly
Ok so my husband's semen analysis is normal so my gyno will prescribe Clomid now. They left me all the information on voicemail and closed before I could call them back. The nurse said that I have to go in on the first day of my next period so I can start taking it on cycle day 3 but she said the problem will be that they will be closed a lot in the next few weeks for the holidays so that could push me back to January. Why can't they prescribe it to me now so I have it on hand and then when I start my period I could just take on the 3rd day? Why do I have to wait to start and then go in that day to be prescribed the Clomid?