I've been trying to track it. So far here is what I've been able to put together
Building 8, 90's, started renovation on 6 March, opened on 8 June (~renovation time 94 days)
Building 9, 80's, started renovation early May, scheduled to open 24 July (~renovation time 80 days)
Building 7, 80's, started renovation early June, scheduled to open 14 August (~renovation time 70 days)
No other buildings have been started but guestimating building 10 will be next and should be started in the need week or two, with building 6 being 4-6 weeks behind it.
It appears that they are getting faster as they get more familar with what they need to do.
I am guessing that by the end of October they will be finished with 10 and 6 (the 70's buildings) and will be working on 4 and 5.
EDIT: Fixed the open date of bldg 8