Flats can be done the next day as long as you leave your focuser and lens untouched. If your focus changed throughout the night it does not matter as long as +/- change was minimal. You can use something like an iPad with a white screen placed on the dew shield when the telescope is pointing straight up. My ES refractor’s dew shield tends to walk it’s way down on with the weight of an iPad, so I use a large rubber band directly behind the dew shield to keep it from moving. You can sometimes get away with using a set of flats multiple times as long as any dust on the lens an/or camera sensor has not moved.
Mounts: ES PMC-8 G-11, ES PMC-8 EXOS-2
Scopes: ES ED127 FCD-100, ES Levy Comet Hunter, ES N208CF, QHY Mini Guide Scope, Solomark F60 Guide Scope
Cameras: QHY600M, QHY128C, QHY168C
Misc: MoonLite CFL 2.5 / High Res Stepper / V2 Mini Controller, Baader SteelTrack NT / SteelDrive II, Baader UFC, Optolong 2" L-Pro / L-eNhance, QHY CFW3-L, Baader 2” LRGBSHO CCD
Imaging Software: NINA, APT, SharpCap Pro
Processing Software: PixInsight, Lightroom, Premiere Elements