It's not too late, however, if you can get it in sooner, the better. The verification process can take 6-8 weeks. I know I submitted mine at the beginning of June and I still don't have my app verified yet. If you apply on June 30th then your app might not be verified into end-July-August. Then you have secondary applications after that to submit.
IIts best to submit your transcripts before you submit your app so that they arrive and are processed quickly. Also, you can submit your primary app without having your MCAT score or LORs yet.