De or het winkelopening?

The correct Dutch article is:

de winkelopening

Rule Words ending in -ing: almost always de. See the rule

How to use winkelopening

the winkelopeningde winkelopening
this winkelopeningdeze winkelopening
that winkelopeningdie winkelopening
our winkelopeningonze winkelopening
your winkelopeningjouw winkelopening
every winkelopeningelke winkelopening
which winkelopening?welke winkelopening?
a big winkelopening / the big winkelopeningeen grote winkelopening, de grote winkelopening