Your mechanic should have removed all the Freon, pulled vacuum, and added exact amount of Freon using weight. I would not do anything else for the variable speed compressor with TXV valve... Charging by pressure is not a wise thing to do. And - get pure Freon without oil or any additives. It is not too late to do the procedure I described - better than replacing $2k+ compressor down the line...Of course immediately turned off A/C after a few minutes and mechanic drained it and charged to appropriate pressure. Everything's working fine running A/C for 2 hours --- but warning to others. Those cheap ($40) charge kits from Pep boys have unreliable pressure sensors or something.
If anyone knows what the temporary smoke/smell was let me know. I read in other forums that overcharged air conditioners always shake the car.