Stop using the miracle grow as there's a lot of nitrogen in it. Try using a 2-10-10 Bloom special made by sunniland or other companies.It's NOT bloom booster.
Sun to 2pm should be ok. We've had a cool spring so far so that may delay the flowering. Mine's in a black pot and so the roots are running warmer. It's just starting to show flower shoots coming out from the sides of last years shoots.
kevin

Cestrum is happiest with a lot of warmth and sunshine, so it may not get going until later this spring. Also, don't prune it back any more, it blooms on new growth!

Jim