Timing the tulips with the festival is always a dice toss. In recent times, they often bloom before the actual festival but this may be the 1 in 6 yrs when they don't, or even the 1 in 12 yrs that they're late. City of Holland or tourism beaureau has a live web-cam on a sample plot of tulips so you can monitor the progress. Can't change it ofc, but at least you know what to expect. Before the web, it was a real crap shoot to know when to make the trip? Regardless, great city/region and you can't help but have a good time.