Ok good info. I will ensure I really mix up the pre boil wort before taking a reading. I'll also wait until the wort is really mixed up in the carboy to draw a post boil reading.
Unless you do a small boil and top up, there's no reason to worry about mixing post boil. For the preboil reading, just wait until it boils for a minute or so then take a reading. The boil will mix it thoroughly.
im a refractometer guy.for me, i can say having taking multiple reading at different points in the process, that accuracy and consistency of the gravity readings were when post boil was cooled, trub settled, transferred and then take my final reading (refractometer compared to hydrometer).