HRT - have them. Don't know if I should start now or wait?

[bulletproofgerbil]

Just that really. I have been prescribed Elleste Duet which I think are for women who still have periods. I've been told I should wait till period starts and then start taking them. But my period is a bit irregular so I don't know when the next one is due.

I am having hot flush after hot flush and feel like shit and want to start them. Is it vital to wait till period starts. Does anyone know what would happen if I begin now? I'm desperate to feel better than this. Tia