I don't think there is a right or wrong -
If I recall, the DJ didn't start talking right away. Most people go to the reception, mingle while they look for snacks or drinks. When your wedding party is done with pics and arrive at the hall, you can have the MC give a five minute warning to find a seat, as the wedding party will be announced shortly. Most people announce the couples in their wedding party as they walk in and go to the head table. It took us a few minutes to get settled, and we had to wait for dinner to be ready, so people just chatted until they announced dinner. You can have the MC give another 5 minute warning to find their seats again as dinner will be served soon.
When the potluck is all set up and ready to go, have the MC announce that the toasts are going to be made by Persons XYZ. When they are done, MC announces whoever will be saying the dinner blessing. Head table goes up first, make sure you have someone to let the other tables know when it is their turn to go up. You don't want to do anything else until the last table has been served and has had a chance to eat. Often the timing works out that the head table is done eating before all the tables have been served - we started going around to people at the tables while they were eating to thank them for coming.
When the MC sees that everyone at the last table served is about done, then the festivities can begin - and I don't think there is a right or wrong order there. We chose to cut the cake next - the MC announces that so whoever wants to watch/take pics etc can go to the cake table. We took a few minutes to clean up after that, then got the party started with the dancing.
You might want to think about singing your song first when the most people are still likely to be there. Then everyone can go "AWWWWWWWWW
", the bride blushes
, and the MC can announce your first dance together. The second song is usually when the wedding party is announced again and the couples dance together. 3rd song is usually an upbeat dance song to get people out on the floor. Play another upbeat song or 2, throw in a slow one or 2, then maybe a group thing like a dollar dance (if you do that) or the Chicken dance, hokey pokey etc. Another regular song or 2, then the bouquet and garter toss - people usually do them back to back. Then just going back and forth between faster and slower music until about 20-30 minutes before the hall says you have to be out by - this way you have time to get your stuff out of there. There is always a last song, MC announces that so people know this is their last chance.
I have never seen a grand exit - doesn't mean you can't do it though. It just often ends up that at the end of the night, there are usually only a few diehards left like family and the wedding party. The reception staff will likely be breathing down your neck to get your stuff and get out so people help get things out to the cars.
There really is not a right or wrong for anything - it is your day, you two do whatever your little heart desires
If any of this is 'like duh' - I apologize
This is just basically how ours went and how the majority of weddings that I have been to flowed...