Hi linda,
Tricky question as it depends on a couple of factors when it comes to a neo colouring up. It depends which neo it is as some are very hard to colour up. I can move a plant around my place about 5 times before i get it in the right position. It is more about "light" than direct sun when talking about colouring up. You can have a plant under a tree which is getting dappled light and they look great. Most neo's can handle morning sun but not afternoon sun as it is more harsh.
Regarding fertilizer i give osmocote when i first plant them in pots as when they are pups they take their nutrients up thru the roots. As they mature the brom takes it's nutrients in thru the well and the roots are used to hold onto whatever they are attached to. At this time you can give a dilute soluable fertilizer but it is hard to get right. If you give it too much soluable fertilizer the brom will go green and leaves will go strappy and it will take a long time for it to recover.
I would be patient and try a different pup in a seperate area of your place to see which looks the best, then you will know.

Hope this helps
Dooley.