I have several questions about tire pressure.
1. When should you check tire pressure?
2. How long do you have to wait before you check your tires (after you have been riding?)
3. Where can I buy a good tire pressure gauge?
If your tires and valves are OK and there are no plugs, never. However, to establish if the tires and valves are OK, I would suggest once every month or every two months.
When it is cold outside, I generally do not wait. Also, I think that tires of small scoots do not heat up that much, especially not in the winter. Furthermore, when the scoot is sitting in the sun, black tires and air inside is already sizzling. So, I would not lose sleep over all that. Big bikes on track and those that develop 100 or 200 hp are a different story.
I have el cheapo Chinese one with LCD for a few US$, works like a charm.