It's normal for the system to equalize. The gas simply makes its way through the expansion device - orifice or TXV - through the evaporator, and to the low side service port. You cannot determine anything about the condition of the compressor; nitrogen could be leaking back through the reed valves or not, you cannot tell the path it is taking to reach the low side.

When charging an empty system, I generally liquid charge through the high side port into the vacuum with the engine off. The system fills really fast that way. When the low side starts to equalize, I'll stop charging, switch on the a/c, and evaluate the pressures. The charge can be topped off by vapor charging through the low side port.

- JimY