Converting Principal residence to rental

I rented the property prior to mandatory declaration of deemed disposition (In 2014). I did not submit the election under section 45(3).
Do I have to do it now or wait until I sell. It is still rented out
If I have to do, is there a specified form or just a plain letter will do.
I also did not do proper appraisal. Will the market value or houses sold in the building suffice.
Any suggestions

Since ITA S230 mandates proper record-keeping for business and property income, the client should specifically hire the accountant to maintain and/or correct the record keeping of this income producing property for all years, beginning with purchase and start of rentals.Possibly zero years are available for election.

Oh boy…some of the queries on here…