My two daughters are 29 months apart. So DD#1 was 2 years and 5 months when DD#2 was born (perfect age gap in my opinion).
My DH is a firefighter, therefore works shift work - away all night for 2 nights a week, which means i have to put two littlies to bed on my own.
Didnt even think of a routine when DD#2 was first born, and knew it was silly to introduce one so early. So first 3 mths DD#1 stuck to her routine - in bed, book and teeth by 7pm. I then dealt with DD#2. After 3 mths DD#2 gradually was getting into a sleeping routine. So now i:

BATH - 5pm
DINNER - 530PM
PLAY - 6PM
TEETH/BOOK/PACKUP - 630PM
SLEEP - 7PM

I read DD#1 a book lying on her bed, with DD#2 inbetween us. DD#1 happily says goodnight, i shut her door, then breastfeed DD#2 to sleep in her room.

THis works for me, may not for you. Only thing that worked for me that i thought was good advice, dont expect a routine in first 12 weeks of your newborn....just stick to your routine you originally had with the older child.....your second child will gradually fit in....