Why? What would waiting do for you? They aren't the same game. If you want to play than play. 2 to 3 hours is plenty of time depending on the content you want to do it and the time of day you have that gap. You might face limits finding a raid, you certainly would if you inly had 2 hours. As for the fun or enjoyment you might have nobody can forecast that for you.
- - - Updated - - -
Not at once. 3 hour blocks are the norm pretty much everywhere. I play on one of the larger servers and only 1 guild goes longer than 3 and they push for top 100 each teir.