Re: Mehndi vs Mayoun
traditionally (at least in urdu speaking families … not sure about punjabi) … mayoun happens first … in the olden days … t was meant to be a sort of a rest period for the bride during which she is exempted from all housework, puts on a simple yellow jora, stays out the sun … infact doesnt go out at all… and kinda just focuses on self pampering/time with friends/family. mayoun used to be as long as a month! (grandmas time) … my mom was sat mayoun for10 days … she hated it and instead of being able to relax she cried the whole time … she tells me :D.
understandable … it was an arranged marriage and she was going to leave her hometown to be across the country…
anyhow … traditionally on day 1 of mayoun … grils/ladies gathered to apply ubtan, oil to hair etc … its supposed to be a mini party at home with music and a bit of dholki … not a 50K party with photoshoots 
… its literally the bride to be with a plain face getting oil/ubtan rubbed on her legs/face etc… no makeup/jewelry etc…
at the end of mayoun … comes the mehndi … a bigger party/dress up/music/clothes/dancing etc… and traditionally the dress code is yellow/green with flower jewelry and application of henna etc…
remember this is what used to happen “traditionally” …
these days … there isnt really a defining line tween mayoun/mehndi. the bride to be ends up looking pretty much the same on both days … give or take a few color changes OR is so overdressed for the mehndi day that it looks like a barat day …
bottom line … do what you like. There are no real rules to this.