The medical situation is causing a lot of confusion. You do not need to get your medicals done in advance. Apart from the visa application itself this is probably your next most expensive item. Your not required to complete them and pay that expense until requested by your case officer.
You can of course get them done at some stage throughout the waiting process but that depends on how confident you are about the application made and how smothly it's going. Many people do this after acknowledgement of the application, you get your file number and so on. This can help as clearly they then have your meds and X rays in advance instead of having to request them from you. same applies with Police checks. Remember you have 1 year from the date of the earliest item of these two (meds and Police checks) to get an answer, or else you have to repeat that particilar process. More expense, so be careful how you judge it.
BOB
