I started submitting pictures to microstock almost a year ago and I am reporting my progress, earnings and actual payments with some graphs in Pixels Away photoblog.
Dreamstime was showing a pretty steady performance during last months and in October (50% increase) it took a solid third place afer SS and IS providing 12% of microstock income. Uploading 70 pictures certainly helped. It seems that in other agencies my increased efforts in producing and submitting pictures didn't bring the expected return.
I needed 9 months to reach the first payout from DT. I am hoping to get the next one in 3 to 4 months. And, one more thing: DT seems to be the only microstock site which really works for me concerning a referral program, both for photographers and buyers.