Ceiling lights (fluorescent) takes too long to light
First, a little bit of a slow start is a good thing -- that is a better-quality ballast "soft-starting" the bulbs.  They light up pre-heaters in the ends of the bulb before striking the arc.  The best programmed-start ballasts actually measure performance, so they know to give the bulbs longer to start.  But this is not that.   To troubleshoot this: 


Change the bulbs, unless you have tested the bulb good in another fixture. 
look around for a "starter" and change the starter if it has one. 
Replace the ballast with a modern electronic ballast.  In this case, if there's a starter, it will be bypassed.  You can leave it in place to avoid an ugly hole.  


Far better to get an LED "tube" which fits in the fixture you have.  I recommend getting "direct wire" LED tubes, in which you rewire your fixture to bypass the ballast.  (Don't use "ballast ready" or "drop in" types, because they require you to keep the ballast in the fixture, and it must be working, and it must be a very particular type 0 which is more trouble than it's worth.)