Great questions. Yes, you can just slide the slider forward. Your fuel load is entirely up to you, so you can pick the min or max fuel loads. But any spare weight between your fuel load and the MTOW, you should fill with as much cargo and passengers as the plane will allow (without going over MTOW).
As for the start time, we all stay cold and dark until 0800 Local, then we all start a the same time. No programming the FMS either, no batteries.