Ok so i noticed some fading on my leaves this morning and after reading up its most likely a ph problem so im about to go buy a ph meter, anyways my question is i watered my plant about 2 days ago and the soils still moist, would it hurt it to flush it and test the run off or should i wait til the normal cycle of watering before testing?
Flushing will saturate the soil anyway. You want to avoid leaving her soil saturated for multiple cycles, as that can cause stem rot and leeching. Basically, you just don't want to water every single day (If she doesn't need it). So yes, you can flush now without any problems, just make sure you let her soil get good and dry about 2" down before her next watering.
I would wait !!! Why take the chance ? A plant can be overwatered with just one time watering to soon, although cannibus is very forgiving.