Start crate training! I've had Bella for two mths (she's almost five mths old now) and I started crating her right away. She does really well, and sleeps through the night. Only once or twice when we first got her, she woke us to go potty.
She did whine the first few nights in the crate, but only for a little while and I ignored her. She'd also whine/bark when I got up to pee but I ignored her then as well (yeah, I know... seems cruel
) but within a week or so, she had stopped whining completely and goes straight to sleep.
Good luck!