My 10 month pup is in heat?? what do i do? plz help!?

I have a 10 month old golden retriever, she is scheduled to be fixed in 10 days. and just today i started seeing blood. im kind of freaking out, i have never had to deal with this b4. my other dogs are fixed but im worried if there is going to be a lot of blood. she sleeps on my bed and that's how i found the blood, there were a few drops. is it going to get worse? sorry if i seem frantic this is just my first dog that i actually raised from when she was born. do i get diapers? OH and how long does it last? bc i was told that they cannot fix her when shes in heat. so id like to get an IDEA of how long it is to know if i have to reschedule. please help and thank you.