Getting a puppy is a bit like going back to having a newborn, although not quite as exhausting and emotionally intense, and the developmental phases go by much faster.
You should plan on having disrupted sleep, someone will need to sleep next to the puppy for an impossible to define length of time - some puppies get the hang of sleeping alone in a few days, others take months.
Prepare your house for toilet accidents and chewing. Ideally floors should be hard surfaces that are easy to clean effectively (enzyme cleaners are excellent for removing urine). Keep one room puppy safe, with all toys and plastic stuff removed. Get a crate but be prepared that it will take a few weeks for the puppy to get used to it.
Look into puppy socialisation classes and basic training classes using positive reinforcement techniques. Ideally visit the classes first to check the training methods out. If you are not familiar with dog training, look up videos and advice online, dog training starts on day 1, not at the first class.
Get the puppy vaccinated ASAP and meanwhile carry it outside to see the world. It can also safely meet other vaccinated dogs.
Be prepared for your DCs to loose interest quite quickly and even find the puppy annoying as it will chew their toys, pull on their clothes, eat their food, nip them and scratch them.
I hope your breeder has carried out health testing for both breeds used and has shown you the paperwork. This is a minimum standard for any breeder.
Lonecatwithkitten 1859?!!! 