Suggested introduction period - put the boots on your horse at a time where you can supervise for approx 1 hour. If you notice your horse getting fidgety, remove the boots at this point. It's just a reaction to the circulation starting to move more which can feel somewhat tingly for the horse until they get used to it.
The next day, repeat this exercise and see if you can get to 2 hours. Repeat this on the 3rd day and after that you should be fine to leave them on overnight or for longer periods unsupervised. The supervision is so you can interrupt and remove the boots if your horse is getting particularly fidgety which could result in scratching or stepping on the boots. On first uses of the boots, some horses show a little filling, this isn't something to worry about, just shorten the length of time the boots are worn in the initial week of wearing until it settles down and you should see the opposite then in future use.
The removable liners that can be washed in a cool wash (max 30) on delicate cycle, gentle spin and line dry. Use non-bio wash, wool wash or Rambo Rug Wash.