Calibration at PCB is often only way to reach any accuracy if working above few 100 MHz and want good accuracy but there are many problems related to do this calibration.
Ideally is it enough to do port forwarding, compensating for the added cable and maybe a short length of PCB trace and maybe empty component pads, to reach actual measuring point, typical a active circuit port or location of a passive impedance matching circuit.
Result of this port forwarding is often poor, so next step is to do a calibration directly at measurement location at PCB.
Most professional calibration kits, have internal parameters loaded in VNA as these kits includes an offset, either in length or as added fringing capacitance or both. It makes them less useful to be used with home-brewed calibration components.
A possible solution is to temporary switch to user defined calibration parameters in VNA, it will give better result but it is not ideal either, to calibrate with none-offset parameters.
A somewhat better way is to do normal calibration but also include same type and length of semi rigid coax as was intended to be soldered at PCB, but now including connector fitting you calibration kit and finally do a port extension.
It is not the best to include a extra connector in calibration process, and then exclude it in actual measurement and at PCB, even very short PCB traces and pads can create problems if you not want to include them in measurement, and these will not be compensated with this method.
If working above 2GHz can resulting error be huge.
To solve these problems, I recommend my own Win software,
AnTune. It is free to try and is fully functional in trial mode. AnTune require a GPIB, USB or LAN connection to the VNA.
AnTune have automatic port forwarding settings, not only as a time-delay but do also calculate a complex network to linearize for stray capacitance or inductive losses in PCB traces or attenuation in measurement cables.
It is very simple to use, just push a button while shortcutting measurement point and AnTune will then show live calibrated S11 result.