Ours were kittens when we got them, but we confined them to one room for about 24 hours with regular visits. We also used cat litter and food they were used to, firstly to help settle them in but to limit any problems with using the litter tray and food. As mentioned a Feliway diffuser can us useful for stressful situations. Your vet may be able to supply it or you can buy it cheaper online. Some cats will look for love and attention immediately, others may be a little more restrained, so let them set the pace.
By the way, the second night we allowed them to come into the living room with us and gave them their own space to investigate.