I would put all the coals I was going to use in the basket before I put the lit coal on top of the pile of unlit coals. I have never had a white smoke problem except when I re-used some briquets that had already been used prior to the present burn. Don't add any coals after you dump your chimney, unless your fire has been burning for a good long time and most of the coals are already lit.
Moisture from bags of charcoal that have not been stored in a controlled temp area will absorb moisture and cause white smoke. I won't buy charcoal that is stored outside in a display at any location. I only buy what is stored inside the store. Good luck in your search for the problem.
Webber 22 1/2 OTG Gold, UDS, rusted out chimney, yeller wannabe thermo pen, Maverick ET 732, 1950 model wife. Walking cane to help me get around.