Can't believe I have reached the point in my life that I am going to post such things but........... NEVER throw a leg over the seat without a helmet, period. On the track, trail or in the backyard, protect your head. Looking back over 40+ years of riding, most of my ugliest wrecks have been on quickie/spur of the moment rides from or at home. Have had plenty of wrecks on the racetrack without a significant injury. Today's safety gear is light, comfortable and effective.
Your balance will be better with your feet on the pegs. It also puts you in a position to use the rear brake when that powerband hits a little harder than you thought it would. Also allows you to work through the gears when it all comes together.
Keep on riding! Safely, of course...