The decrypter does seem to take a while. I had everything done in an hour, but we had only about 80 files that needed decrypted - total of around 200MB. Most files were under a MB, the largest (and most important) was 23MB.
Thankfully, I had good backups of a majority of our stuff, so I didn't have several GB to decrypt.
If it's any comfort, I don't think the decrypter has a time limit where it will stop working. On a whim yesterday, I ran it again on an encrypted file - it still worked 2 days after I downloaded it.
That's interesting that you had to wait overnight. I seriously think it might take a live person on their end to approve the transaction and give you the link. Given the bad English on their website, I suspect they might be in Eastern Europe or Russia -- around 6 to 8 hours ahead of me here in Ohio. So if you were, say, on the East Coast of the US and paid their ransom at 8PM our time, it would have been around 2am to 4am their time... they were fast asleep (or passed out drunk after spending their ill-gotten gains).
Anyway, yeah, after I got the files back, I did all three of those things - anti-virus (MSE and Avast), Malwarebytes and did the cryptoprevent on all the PCs that access those shares.