You can do your medicals upfront but they need to be valid for a year. For PCC in India don't count on any certainties, i expected to get mine the same day but i had to go thru physical police verification for no apparent reason. The police station said they do the back office processing only from 15th to 30th of each month. It has been a month and still waiting for it. Thankfully i submitted my application with a LOE and proofs that i've applied for PCC and got an extension of 60 days (i rejected an ITA once for FBI PCC taking 4 months).
Since your score is good i'd say get on with it and start collecting your documents. Medical can be done in a day but PCC is a big hassle at least in Ahmedabad.
Yes you can get it done before if you are sure you will recieve ITA. My medical and PCC took at max 3-4 days. In india it is pretty easy and straight forward. Other documents might take much more time such as proof of funds, employment records, your travel history, your personal documents etc. So make sure you have those ready. The earlier you get AOR, the better it is