score:3
I guess you mean the Hallerbos (Vlasmarktdreef) near Halle, Belgium.
In that case their site will help you out, (if you can read Dutch or use a translating service.)
The last posts I find mentioned that the Bos Hyacinten (the local version of Blue Bells) are out now. Knowing the flowers it is very likely that you can still enjoy them in ten days time but if the weather turns very hot or there are torrential rains you might be out of luck.
In that case going as soon as possible might be better. (Check out the site for updates.)