Bart, I would imagine the A3s come with metal coasters for under the spikes. My advice is to pick them up from Goodwins, set them up yourself, let them break in with digital music on a loop 24/7 for one week (168 hours) or ten days and then schedule a time for Goodwins to come over and fine-tune the set up/speaker placement. It might even be fun to set them up yourself and compare that to what Goodwins does.
It is fun to do the initial work yourself, at least when the speakers are of this manageable size. Unpack them, inspect them, move them, read the manual, etc. Use this time to get to know them as objects and appreciate the build quality. Then schedule set up with Goodwins after they are broken in.
I don't know how exacting Goodwins is, but I am a big believer in using a laser and experimenting with all parameters: distance to front wall, side walls, toe-in, tilt, etc. The more accurate the better. Use a variety of your favorite music. I found that it took me about a month to get to settle on one position with my Q3s, as every slight movement affected some sonic attribute.
While they break in, you should be able to locate the best spot for the listening seat based on smoothest bass response. Also play with seating height. I suggest an office chair on rollers for experimenting. Move your seat to that spot, so Goodwins won't have to deal with that unless you ask them to confirm it. It can all make a difference.
Congratulations, and enjoy the process.