How do you write a jump cut in a screenplay?

Would just JUMP CUT as a scene heading suffice, or would you just do a normal Cut to: and then repeat the scene heading?

For a scene to change, either the location or the time of day must change. In you're case, the location is staying the same, but the time of day is slightly changing, right? So you could put something like:
EXT PARK AFTERNOON and then EXT PARK LATER THAT DAY or EXT PARK 5 MINUTES LATER or something like that.

The "Cut to:" is normally not used anymore because it's implied when changing scenes.

By putting "Jump Cut" in, you're intruding on the director and editor's job, which is a no no. You just need to write it so they are forced to use a jump cut. ...If that makes sense.

Yeah I get what you mean, cheers for the reply.

Although this is a shooting script for my own film, I'll bear that in mind if the time ever comes when I want to try and get people to read my scripts.