Yeah, as others have said, there's no real average, so many variables are in play here, like the sensibilities of an individual agent, versus the time of the year of you're submitting. I had one agent request a full from me within an hour of my sending a query. She never, ever responded to me again. On the other hand, a query I sent out and forgot about, didn't get a request for a partial until two months later, then didn't get a full-request for three months, and that finally turned into an offer of representation two months after that.