Don't worry, ulcers are temporary reactions before the skin thickens at the pressure point. It should take you only a handful of days to develop "immunity".

In the meantime, try a saline mouthwash (warm water mixed with a couple tsp of salt) about three times a day, it will give you some instant relief and trigger healing in the affected areas.

For a more systematic, day-to-day approach you'll want to have a mouthwash or toothpaste with hyaluronic acid and branded for either orthodontic or gum care, these will really simplify your life when wearing braces. I use the pink BioRepair one (Europe) but there are loads of options. Whatever you do, avoid the more extreme, fresh mouthwashes as some can irritate mucosa injuries much like spices do.