You have to wait till the paint cures, otherwise trying to machine polish will either straight out strip it from the surface, or you will not be able to actually polish the paint, because it will not be hard enough for the abrasives to do their work properly.
How long the cure takes depends on the paint, temperature and humidity. If you only did tiny spots, like rock chips, then you should be fine in a few days max. However, if you did larger areas, curing might take longer (as in a week or more) and you will want to be more careful with the polish, in order to avoid stripping the newly applied paint (especially that you obviously didn't use any primer to help it bond).
Also be prepared to have to repeatedly apply some paint after the first wet sanding, because during the latter you will most likely uncover tiny air/gas pockets in the paint, which then you will have to fill up with the repeat application, and then after letting that new coat cure too, wet sand the area again, until you get a fairly even surface, without having to sand down a serious amount of paint/clear coat around the touched up area.
