No effect as long as between your landing date in 2016 and 5 years later from landing date in 2021 you can show 730 days in Canada when comes to renewing your PR card.
As has been said many times on here do not confuse PR card start/expiry with residency obligation , the important date is initial landing date and the 5 years from that date. Also when leaving Canada do not forget to take your PR card as you will need that to board a plane to return