So doing some quick digging from last year, there almost has to be a flood of invites that will come out tomorrow or one of two things has happened:
1) GMATClub applicants are suddenly extremely uncompetitive or
2) Booth is interviewing FAR fewer applicants this year
I say this because, according to the class of 2018 thread, the number of first round applicants that have a status of "interviewed" (I believe this doesn't even count the ones that changed their status from Interviewed to Accepted/Matriculating/Dinged) is 119 out of 275 applicants. There are 285 applicants in the first round this year, so I believe it's reasonable to expect approximately 120 or so invites from that, which so far it appears there are only about 30.