There are several issues that may affect the acquisition time. Generally, it will be best if you can start the GPS receiver and antenna under clear sky because initially satellite data such as ephemeris and almanac must be transmitted to the GPS receiver during acquisition phase. The amount of time required is dependent on how much of the satellite data already stored inside the flash memory of the GPS module is usable.

Once the position is fixed, you can move it to an area where the reception is poorer as the tolerance for GPS signal clarity is less strict due to the way ultra-sensitive GPS modules are designed.