Go to girls' locker room.

You walk into the girls' locker room and open your locker. While you're starting to undress, Julia walks up to the locker next to yours.

"Hey, Parker," Julia says, "I'm surprised you're still in boys' clothes. I thought that since you decided to be in the girls' gym class that you'd have come around by now."

The two of you are about to change into your cheerleading outfits when Rachel suddenly appears. "Parker, what's with those clothes? Doing a little cross-dressing when you're not in your cheerleader outfit? You should really get a proper wardrobe. Still, happy to see you back with the girls. I'm keeping an eye on you."

Rachel stalks off without waiting for an answer. You take off all your clothes, including your underwear. "Parker!" Julia says. "You're fully transformed! I didn't think you'd have a pussy this soon. I don't know what it's like to have a dick, but I think you'll like your new equipment much better." When both of you are finished changing, you head out to gym class.