Hi, I'm also in agreement with Moek90. I (principal applicant) received my OWP approval this past Friday. A few days before the OWP (I didn't know when I was actually going to get the OWP approval), I went ahead and completed my visitor extension (I only need a visitor extension, not a visa extension) because it was going to expire in July and I wanted to ensure that I was going to be in implied status as a visitor (temporary resident), in the event that something might have gone wrong with my OWP application or with my PR application. I completed my visitor extension application and payed fee online. 5 days later, I obtained my OWP approval; oh well. At the end, I think it's best not to chance it, and it gives you peace of mind, knowing that you are doing your best to keep your status. This is only my opinion of course.
Hope you have a great time at your reception with family and friends!