The May 2020 deadline outline in Reg 2017/745 is a cutoff for new filings under MDD, the previous regulation. If your product is already CE Marked under MDD, you do NOT necessarily have to re-certify by the 2020 date, but could keep your product on the market up until May 26th 2024.
If your product is already CE marked and no large changes are planned in the next several years, then it is perfectly reasonable to wait to re-certify until closer to the product’s expiration date.
If your product would benefit from further clinical data being gathered, then it also would make sense to wait longer before re-certifying. This is a judgement call that can be determined by a preliminary risk-benefit review. If you determine that more clinical evidence would strengthen your application, then waiting can be a wise decision.
The important thing to note is that the date of application in 2020 is NOT a hard cutoff for your existing products, but it is an important data point to consider when defining your MDR compliance strategy going forward.
Another thing to consider is whether or not the notified bodies will be able to keep up with the influx of filings and CE Marking requests over the next several years. While it is true that according to the regulations you may be able to delay filing past next year’s deadline, in practice it may not work as intended. There is a very real possibility that your product’s MDD certification could expire while your MDR paperwork sits in a queue waiting Notified Body Approval.
Of course there are plenty of variations in between certifying today and waiting until the deadline, and likely your organization will fall somewhere in between the two extremes depending on the amount and classifications of your product offerings.