I have noticed that older hamsters do tend to adjust more quicker, than babies. How ever, I do not recommend getting any older hamster than max 1 year of age, if you want to get an older hamster. Moving around hamsters that are over 1 ears and 2 months to 2 years old can get pretty stressful and the older they are the more stressful it is for them.
When you go get a hamster, wetter it is a baby or a bit older one, have a suitable transportation box, but bedding (wood shavings), some ripped toilet paper. A toilet paper pipe is also good if they feel uncomfortable and want to hide. Some seeds in and a piece of cucumber is always a must to put in the transportation box too, so they get liquid when they get thirsty and something to eat when they get hungry…Also during the winter, use a quilt to cover the box to keep it warm but it should still need to get air…🙂
Also bear in mind that if you get an older hamster you will not have as much time with him before he passes away of age, like if you took a 6 weeks to 8 weeks old hamster pup…
How long it takes for the hamster to adjust, depends from hamster to hamster. Some hamsters adjust very fast and can take up to 2- 7 days. Others it can take from 2 weeks to up to 2 months, till they get used with you and the surroundings. Usually hamsters from breeders normally take 2- 7 days to adjust to their new owner and surroundings. But like i said, it depends on hamster to hamster how long they need to fully adjust to their new owners and surroundings.