Medicals should be done
before for Outland sponsorship applications of a spouse, common-law or conjugal partner... Complete the form in Part 3 - Appendix C - and take it along with you to your medical. You will be given a form from the DMP to include in your application package... the results are then sent to London by the DMP... which is possibly the date that has been noted on some profiles "medicals received"...
For complete instructions about your medical examination and how to find a Designated Medical Practitioner (DMP), read the Medical Instructions section in IMM 3999, Part 2: The Immigrant's Guide.
If you include everything on the checklists you can't go wrong
Good luck!