The items you need to have for your pup include:

Coming from a shelter home, away from his companions, and moving to a new house is a big transition for your pup, so don’t be disheartened if he doesn’t respond to your- NOs and OUTs initially. Dogs generally take about 2 weeks to 2 months to get adjusted, some dog breeds may take longer than the others but don’t overstimulate or compare him with your friend’s or relative’s pet. Let him explore around and get comfortable with the environment. Once he feels home, he will come to you and offer you an abundance of affection and love. Building a trust initially is of paramount importance while dealing with a dog. 

The first 30 days are critical where you set the tone of your relationship with him. One needs to define the rules for his and your coexistence in terms of space and freedom and setting up his routine.

  1. Space and Freedom like to restrict his space in the house- to sleep, to play around, to eat, to shit and in the outdoors, in your car, etc. and yet giving him the freedom to be himself
  2. Routine: Dogs are structured animals that thrive on routines and schedules. Adjust your schedule and try to have the same time every day for feeding him; taking him out for leaks or potty breaks;  daily walks and going to bed

All of this might require some training (home or professional) but since dogs are excellent learners, it should be just a matter of time before they adjust to your set routine.

It is possible that your dog might not eat or develop diarrhea in the initial few days but worry not, these are some of the common symptoms related to diet change.  You can reach out to the breeder/ shelter representative to understand his previous diet which you can mix with the brand suggested by the vet before completely transitioning to the new brand. If the problem persists, reach out to your nearest vet. While outdoors, some pups might try to escape, hence try to keep them on a leash all the time till they develop trust in you. Also, keep an eye out for any signs of illness. If you see one, visit your vet immediately, do not try home remedies.