Distance an inverted F antenna should be from the bottom and side edges of a PCB?
The distance from the side edge should be as short as possible, but respecting the mechanical requirement for trace-to-board-edge spacing for your PCB manufacturer.
The optimum position along the edge actually depends on the size of your PCB. If the PCB dimension (what you called the &quot;side edge&quot;) is less than ~6 cm (a half wavelength a 2.4 GHz), the corner location is best. This is to give you at least a minimal quarter-wavelength of ground plane, for the sake of radiation efficiency. Do not expect a uniform omnidirectional pattern however.
If the PCB is larger, then you should center the antenna along the edge, giving you at least a quarter wave of ground plane in both directions. This is more likely to give an omnidirectional pattern, but it will still have some moderate nulls. A full simulation or a trip to an antenna test chamber would be required to determine the pattern in more detail.