Yes, you should normally do that though I will admit to have forgotten to do it on a longhaul recently. But the guys in the Chat service can add the SSK keyword BIKE very easily. They just need to know the dimensions of the box, its weight, and... no batteries, obviously. All in all it's pretty easy. Do that, pack your bike nice and snug (I use pipe insulation and bubble wrap, plus a second bit of cardboard for the fork, and I leave the back wheel on, though obviosuly deflated), add some extra tape around the handling holes of the box and Bob's your uncle.

At T5, I've been directed to almost any desk now - Zone E, zone A, zone B, zone G, anywhere with people - for the check-in part, and the drop-off is at the out of gauge in A and H. Delivery is usually at the very beginning or at the very end of the process, so patience is key.

Kudos for being such a nice person! Can always count on a cyclist to restore faith in humanity.