If you are not staying at one of the on-site hotels, then the best place to park is at one of the parking garages. If you are driving, follow the signs to park in those garages. They are easy to park in and cost, not sure, but check online, as I have a pass that includes parking, so I never have paid for parking. Then you go through security before entering CityWalk. From that entrance, you go left to go to the Studios, right to go to Islands.
If you Uber or other car service, get dropped off at the Hard Rock Hotel. From there, a short walk where you go through security right before going to the Studios, or a short boat ride to CityWalk, with security before you get on the boat. Both security lines are generally shorter than those at CityWalk.
And good thing you bought park to park ticket, so that you can ride the Potter train.
May take advantage of single rider, if available, and stand by line is long.
And if you feel like you want to buy an express pass for all but new Potter ride, and another ride, no one in your party can ride (kid limited ride), it is sold everywhere in and around the parks. Beware though, it is date and park or parks specific, with no refunds.
With that, I hope you all have a great Sunday and Monday in the parks.