My I129F was received on May 13th and I too just got a biometrics request. I went yesterday and got my fingerprints taken. Everything i have read online suggests its a positive sign that they are wrapping things up on the case if the request comes several months after they receive the packet. I assume mine is just to verify criminal history details. Most things I researched say it can take 1-4 weeks for the prints to come back and for them to complete the rest of the information with the average being around two weeks if there are no complications. Good luck!