It really depends on how the flow of traffic is going that day. But yeah, we have been opening Timon around 10AM and closing it around 1PM when it fills up. Then opening again later in the afternoon after guests have left to allow more people to park there.
I have very good luck getting in Timon after work between 5 and 6.
I'm with aashee. I love parking in Timon if I arrive at the parks in the late afternoon or evening. It's very convenient and you get to play the self-parking "how close can I get to the tram stop" game.