Supply question

Hi ladies,

My sisters baby shower is on Oct 6th so I need some milk for the hours I'm gone while hubby watches our son and I also want to start building a little freezer stash.

My son goes to bed around 7-7:30pm and want to pump at 10ish, before I head to bed. I currently don't pump and EBF. My son sleeps through the night until 6-7 so it's used to no 'feeds' during those hours.

I don't plan on pumping every single night but I'm worried if I pump my body will get used to this extra session so once I don't pump my supply will drop. Might be a silly question - would love your input!