S.H.
Keep your eldest child's routine.
With a newborn... there will not be a 'pattern' yet.
So you just have to see.
Regardless... there will be less sleep for you.
KEEP to your eldest child's nap times AND routines as well.
ALWAYS.
Don't change up her routines/special times, just because of baby.
For me, that is what I did. It give the eldest constancy... and comfort. Which they need. NOT being changed up, just because of baby.
BUT... when your newborn naps.... have your eldest nap too. That is what I did... with my Eldest... once I had 2 kids.
"I" also... then napped. Too.
KEEP to your eldest child's routines... as much as possible.
all the best,
Susan