Flying the Citation 10 at the moment... Bit of a beast
It is a beast, true, but it flies like a jet. The 'X' can efficiently descend at Mmo, but ATC might not like it and further down you want to slow down significantly to 265 KIAS anyway (to have a buffer to the overspeed warning).
I like to adapt my 'descent tactics' a bit to my actual fuel status, i.e. lots of fuel on board or short on fuel. If fuel is no problem, start down using the rules of thumb mentioned earlier and you'll have some flexibility if given any 'directs'.
If you have to conserve your fuel, divide the altitude to be lost by 3000 (for a 3000 fpm rate of descent) and multiply this figure with the anticipated average GS, expressed in NM / minute. This gives you a nice fuel-saving descent, but it's hard to get from European ATC.
Your FMS helps you setting up a nice descend by using the Vnav-feature, by the way, and if your 2 boxes are in independent mode, the PF may choose to make calculations using the present cleared route, while the PM keeps her/his box on a route direct to final, for example.