Considering your quite wealthy, why shouldn't you hire all 6?! Your house is big enough to fit 6 people in, and if any nosy neighbors are near it you could simply say you were just hanging out with some gal pals.

Though... A harem of giantess does sound like it could get out of control, especially since this will be the first time you'll meet with them. They would also need to consent to this kind of stuff too, just suprising them could lead to some fatal mistake.

So, with a clear thought, your first action is to talk to each of them. Introducing yourself, payment, meeting spot, etc. Then when your clear all them up you asked the big question. About allowing other prostitutes in.

And with great luck, all 6 said yes. (With some extra money charged on the side).

You'll be meeting all 6 at your house. All of them wearing their best sexy outfit. Because of where you live, noon seems the best time to hook up.

Then came a choice, should you shrink now in order to experience hanging around walking giant women, at risk of being accidentally crushed in your own home or worse.

Or when they arrive, but you either lie or properly explain what you wanna do. Either at risk they overwhelmed your tiny body or kidnaps you when the chance arrived.

(Thinking about it, there is really more you could do to prep better)