He’s conducting the “purge” in logical fashion - after some events occur and so as to not screw with Barr/Durham investigations...Vindman and Sondland were de-fanged and it would have been bad optics to fire them before the acquittal and allowed them to scream more “Coverup” crap.
If nothing else, the President is rationally methodical and prescient with his timing.
As much as I would like to see the traitors go sooner and with more prejudice you are correct. He had to wait but he has not waited long. He has to get this done sooner than later for it to be effective in more ways than one.
NSC has too many people on it now.