Mueller,
From my experiences, the average time for major publishers to respond to a query letter is anywhere from one day (for an e-query) to 3 months. When they respond, they are likely to request sample chapters (unless it's a picture book). The response time for reviewing sample chapters is almost always at least 3 months. When they do respond favorably, they ask to see the full manuscript. I've had full manuscripts under consideration for over a year and I know from my writer friends this is not out of the ordinary. If they do finally get to it and decide it might be worth taking to the top editor (who decides if it goes to committee), they will often first call or email asking if it is still available. They do not want to go to the trouble of bringing it to committee and championing your cause if it's not available, especially if they know it was not an exclusive submission.
So, to your original question and assuming it was a full manuscript, 3 months is bare minimum. Be patient and get to work on the next book.
Oh, and best wishes for success.
Jimmer