Sonoline B Doppler

I just ordered one I'm 13 weeks today after having a miscarriage last July at 20 weeks I'm terrified it is going to happen again and figured this will help give me a little piece of mind in between appointments ... Just wondering how easy they are to use and find a heartbeat after 12 weeks (this is when the recommend use) and if anybody ordered one from how long does shipping normally take I can't wait to get it and hear my baby ( I just heard his/her yesterday at the doctor ) so I'm hoping it comes in the next week !!! Thanks for all the help :)