Based on the existing research, the best bet is to do mouth exercises for at least 10 minutes per day for three months in order to notice a reduction in snoring or OSA. Most people perform the exercises two to three times per day.

Most research studies demonstrate benefit after 3 months

of mouth and throat exercises.  Another study

showed that performing myofunctional exercises as part of a smartphone game for at least 15 minutes per day was effective in improving snoring.

As with any workout, it takes time to build muscle, so you shouldn’t expect anti-snoring exercises to work overnight. The good thing about these exercises is that you don’t need any special gym equipment–you can do them almost anywhere. Over time, regular mouth and throat exercises will strengthen your airway muscles, making them less likely to cause an obstruction.

Sources - https://www.sleepfoundation.org/snoring/mouth-exercises-to-stop-snoring#:~:text=Place%20the%20tip%20of%20your,your%20tongue%20and%20throat%20muscles.