I would continue at least for as long as you can. Keep in mind that different species of snakes can all still spread diseases or mites to one another.
The life cycle of a snake mite is 21 days. You may not even see an infestation until the the 3rd week if the snake was carrying mite eggs to hatch and grow. Or sometimes when the snake is going into shed, the mites that had burrowed under the scales will show up in force.
Reptile metabolism is so slow as well, they can be brewing up an infection during the stress of adjusting to a new home.
I would go 2 months if they were my own. 3 or more for if they were similar species for breeding purposes later on.