The numbers can be found
here.
Through Jan 7:
Total people vaccinated: 443,616
Not yet ready for 2nd shot: 417,055
Already had 2nd shot: 24,200
Overdue for 2nd shot: 2,361 (about 9% of those eligible)
What this doesn't say is what made these people overdue. If the vaccine was not available or they were unable to make an appointment, that would be bad. If they self-selected to not get the 2nd shot (forgot, procrastination, felt ill that day, tomorrow is more convenient, etc) then that's not as bad. It also doesn't say how long overdue they are; it could be that they thought they were supposed to come back on the 8th but were counted as overdue on the 7th. And of course, there is always a question of the timeliness and accuracy of the numbers.
There are over 400,000 in the pipeline for a 2nd shot within the next two weeks. If the overdue number shoots up into the tens of thousands that would give more reason to suspect an issue with availability.