Puppy vs adult
Getting a Doberman puppy gives you 100% control – and responsibility – over the training it gets, the household environment it grows in as well as the amount of social interaction it is a part of. While this is the case, also be aware that you may have to deal with the highest-maintenance period of a Doberman’s life, which is usually until two years of ages. Indoor accidents, potential parasite & virus infections from public locations and other dogs, as well as the time, money & other resources spent on training are only a few factors to consider.
The rule of thumb is an adult Doberman will usually be somehow lower-maintenance, house-trained and relatively well-socialized. Exceptions would be extreme cases of unruly rescue Dobermans coming from abusive or uncaring environments.
Rescue Dobermans should still definitely remains a viable option, though generally recommended for repeat owners. It is also worth mentioning that many rescue Dobermans do not come from these abusive or uncaring environments, but from people who can no longer financially or logistically care for them.
You and your family will not, however, get the same level of bonding with an adult as quickly as you otherwise would with a Doberman puppy that has grown with your household for as long as it can remember.