newbie here

I recently purchased 4 floribunda roses online.
They arrived last week
in 4" pots looking healthy with approx. 6" of healthy, green leaves BUT this week the leaves are yellowing & they are looking poor.
I can't plant them outside here till May & am wondering if re-potting & a sunny window would help plus give them a good 2 months to establish before planting outside in May..?
The instructions said to 'keep in cool area like garage & water weekly until ready to plant' BUT I'm thinking they need Sun.....
...HELP...!!!
