What should I expect if I collect my Non-O Marriage Visa stamp 5 days late?

Any way you look at that, it was sure a fail on your part 🙁

I have seen immigrations cancel the under consideration stamp, charge people for overstay and then sell you a 7 day get out of thailand stamp for 1900baht so you can leave, come back and start the process all over from scratch (getting the Non-O and then 2 months later getting the year extension again)

AND

I have seen immigrations just ink in the year extension like normal, (because at most offices the 30 day under consideration stamp is the first month of your new year extension <- meaning you're NOT on any overstay)

One thing is for certain you need to be at that immigration office bright and early Monday morning .. ..

I will close this thread to stop the trolling once you go and see what's what message me and I'll open the thread so you can post an update

I am sorry this is totally up to the officer; they can be either way. But I mean you have a visa in waiting but you should go the same day.