It depends on you and how different the horse is from what you were riding, I have had my horse for 2 and a half weeks and we are just starting to get a feel for each other. Don't try to jump into something new before you know the horse very well. Just do your best to try to understand the horse. Though if you don't have a lot of experience it could confuse the horse. A lot of it is experience as well as trust.
It depends on you and the hors
It depends. If you have a lot of experience dealing and training horses, then your horse will probably learn fast. It also depends on the horse's experience. If it is young and green and hasn't really had that much experience, it might take a bit of time for it to adjust to you. If it has been fully trained and has had lots of experience, then it won't take as much time.
Absolutely depends on your experiance and the horses experiance. If the horse has been through many riders and many shows as well as lots of training, it may be difficult to understand how to ride it for awhile if you are only beginning. If you are new and the horsenis new it will be difficult to learn training techniques. If you both are experienced and you know much about how to ask it for certain things then it may not take you very long to acclimate to the horse.