First of all have a look at these important dates related to AIIMS UG 2019 Entrance Examination -

Availability of application form for basic registration - November 30, 2018 (over)

Last date of basic registration - January 14, 2019 (over)

Status of Basic Registrations - January 17, 2019 (over)

Corrections of any deficiencies in basic registrations that are not accepted - January 18 to 22, 2019 (over)

Final status - January 28, 2019 (over)

Uploading of prospectus - January 29, 2019 (over)

Dates for generation of code for final registration - January 29 to February 17, 2019

Final registration for applicants with codes - February 21 to March 12, 2019

Issuance of admit card -May 15, 2019

Final registration is yet to be completed. However you can check if your basic registration is accepted or not. Just login to your registered ID (by visiting aiimsexams.org) and then generate the code (if you haven't generated yet). If  a code gets successfully generated, you don't need to worry. As of yet (7th Feb 2019 8:20 AM), AIIMS has not sent any personal emails regarding status of registration.

Thank You

Best Of Luck