All i can say is if you book join in group to to Mytho, Ben Tre at some backpacker travel agencies for a few bucks. It will ruin and waste your day as they all go to tourist's conveyor belt...visit bee farm, local music show, donkey ride etc....
If your budget is okay, let's take a private tour to see authentic
Jun/July is low tour season and monsoon in Mekong. So you can book when you are here
Cheers