This has been discussed many times already, the "Anti-pop up" slider on the Addon Manager does exactly what you asked: loads objects earlier, to reduce loading stutters on final, at the cost of some general fps lost. How much lost, it's obviously depending on the system so, there's no suggested setting: just try the values that works best on your system.
At the maximum setting, everything will be loaded at the maximum scenery range, which is about 10 nm outside the airport.
