At the very beginning, you want to involve the whole family. You want to sit down, have a family meeting, and tell them just exactly what will be happening. You see, this whole experience is going to last several days at least - with plenty of noise, confusion, and dust, and your meeting will give them a chance to ask questions and generally to prepare.
Before those workmen arrive, you will need to get into the room(s) that they will be working on and remove EVERYTHING that is presently there. Not just the furniture - but even pictures on the wall, curtains, drapes, mini-blinds must be removed.
Why do this? Because having this stuff in the room will hinder their work - or it could get damaged while they are in there. Make sure that everything that is moved out can be left in it's storage location for a while, as you will not be able to go into the room while the finish on your new flooring is drying and curing.
Do you have pets? If so, you will need to make special arrangements - either to keep them securely corralled in another room, or better yet, have a neighbor, friend or family member watch them for a few days. You don't want to take a chance on them getting loose and tracking paw marks or leaving pet hairs on your new floor.
Speaking of floor finishes, after your hardwood flooring has been installed, and it has been sanded and finished, you will need to just leave it to sit and dry for a few days. During this time, don't walk on the floor, and don't move any furniture back in. Your hardwood floor installer will tell you how long you will have to wait.
But once your floor has dried and cured enough, THEN you can move your stuff back in. As you do so, take care to put some pads or floor protectors under the legs and bottoms of the furniture.
As you use your new hardwood flooring, don't mar them by walking on them with hard-soled shoes, athletic shoes with cleats or spikes, or high heels. To protect well-traveled stairways and entrance ways, cover those areas with good-quality rugs or mats.