is there a way to schedule a turn-on-wifi-sync-turn-off-wifi scheduled task for every day at 8am?
Of course there are tons of it. Many of them just supports what you are asking but I'd recommend you llama or tasker. Tasker is paid app but llama is free and uses your cell tower to determine your location to make location based tasks as well. For eg, not only it can do what you have asked but also only when you are at your home.