Hi Karen
I would say that you should think about where you want the pup to sleep as an adult. Think very carefully - the idea of a dog in the bedroom might sound ok, but be aware that dogs scratch, fart, move around, lick themselves noisily, snore, have noisy dreams (kid you not), smell doggy and so on. And bear in mind that a large breed dog is going to produce more of all the above than a Min Schnauser! IF you (and any partners, present or future!) can deal with all that permanently, then go ahead and have your pup in the bedroom with you from the beginning.
But if you think that sounds like too much to deal with, then I would advise you to keep the pup wherever you want it to be as an adult, but sleep in the same room as it for several days, perhaps even the first week. Make up a bed there, or sleep on the couch. By then the pup will have got used to being away from mum and littermates and settled in with you, and you can go back to your bedroom!
I would also advise you to use a crate and crate train your pup. This makes the whole toilet training thing a lot easier and you can also go to sleep and know that nothing will be destroyed or messed on when you wake.
You should get up regularly to take her out and NOT wait for her to tell you, because that way you will be rewarding barking or noise. At any time you should not let her out if she barks or makes noise - you should anticipate her needing to go out. At 12 wks she could probably go right through the night but you might not want to try that the first few nights, so set your alarm, for say 2am and let her out then.
http://www.ddfl.org/behavior/crate-train.pdf