I don't sell. I've only been soaping for about 10 months. I'm not ready to sell, if ever. But I think about it a lot. Like, if I could win the lottery I think I would open a bath & body business.
Okay so with the term "lead time" I assume you mean that would be the quoted time to readiness for delivery to the customer. Working on that assumption, I would consider it bad business practice to deliver a product to a customer and expect them to finish curing it. Especially for a wedding favor / product. There is SO much that can go wrong or be forgotten about in the various planning stages of a big event that they might not cure it for the proper length of time or they could dismiss that as you being superstitious or any number of issues. And if they don't cure it properly then that ends up reflecting on the quality of your product. I would presume that most of these favors would still be branded under your soapery's name. As a guest if I got your soap and it wasn't cured, it'd be a negative experience that I would assume was typical of your products and could result in me never giving further consideration to purchasing from you.
To that end, I would say that yes cure time should be factored in to lead time. So with a CP soap, I would expect a minimum lead time of 6-8 weeks (enough time to order any necessary ingredients or molds, make, and cure the product) before it would be ready for delivery.
As to the CP or MP question... depends on what the couple wants I think. If they just want some simple novelty soaps to be cute, MP might be the way to go. If they want something special or customized, CP so that you can work with them to formulate and possibly even test different recipes. Your base recipe might not be the luxury quality they want. Maybe they want a super luxurious three-butter recipe blend. Or maybe they need a super skin sensitive castille product. In short... if you're comfortable with it, for things like event products be open to a range of different types of soap.