I guess it depends on who you are waiting on a response from, and in what format, postal or internet? It's been a while since I got records from the Historical Archives in Vilnius. But they generally sent an acknowledgement (postal) wihin 6-8 weeks, and then the records came about 8-10 months later. But it could be different if you are requesting just a specific records, such as birth, or marriage. I think the waiting period on those are shorter.
I've been on the other 2 message boards, Rootsweb and Genealogy.com. Are you able to access the homepage on this message board? I never know if the problem is my PC or the web site. Too often the automatic updates to my PC software seem to cause me headaches.