How long can a High Voltage Capacitor in a Electric Oven hold a charge after the oven has been unplugged?
Technically it could hold a charge for years but that's not in real world scenarios. Most likely it will be safe in 2-3 days. I'd still short it before touching it, screwdrivers are cheaper than replacement hands. Depending on how it is wired, shorting the disconnected terminals of the device - NOT THE CAP YET - together will aid a bit.
A fully charged capacitor in TVs, Ovens, etc. can cause cardiac arrest, removed a finger, weld/arc and screwdriver tip to dust; so if you don't have time to wait, still wait 2-3 days if you have time to wait, wait a week.