I went to Chievres this morning.
Two waves departed between 12:30 and 1:00 PM (about 15-16 left, mostly Black Hawks + one Chinook).
The second wave was only made of 8 Medevac Blackhawks.
Around 30-40 (includong 6-7 Chinooks and AH-64s) were still there when I left.
Police was present around the base, controling spotters and asking not to make pictures in the direction /or of the base, nor to stay close to the base itself.
The base security looks to be nervous and sent police to any car stopped around or people not looking like farmers... But no problem with local Belgian Police itself.
During my second police control, they told me where to go to look for the best picture opportunities just after take off, when the shoppers start their flight eastward : first road on the right side (rue de la Croix) on "chaussée the Mons" (N56), in the direction of Lens, after crossing the base's runway :
https://www.google.be/maps/place/Chi%C3 ... !4d3.80609
It was a good advice as the second wave just flew over this spot (a small parking on the side of rue de la Croix, 200-300 metres from the Chaussée de Mons) a few minutes after I arrived.
For those interested, I also saw a good place to watch the choppers at their parking from outside, not very far from the town : enter Chievres by Grand'Rue (N525), then to the left on the Rue de Mons, pass by the elementary school (on the right side) and drive on the small coubntry road, about 500 metres, to a small chapel. At the spot, the sight to the parking looks to be the best. But once again, beware of regulation prohibting filming or pictures...