Better to prepare?

I think you already have the completely right idea about what to do.

It would probably be more comfortable for both the cats if you introduce them to one another in small doses and over a period of time. Definably go with your gut on this one. The old grump might not ever 'like' your crazy young cat but I am sure he will learn to live with him ha ha :)

I'm not sure how well bringing Ichi over again and again will work. Every time Ichy goes over, it will be like the first time. Cats get used to each other by constantly being around one another.

Think about this from Kermy's perspective. A new cat comes over to visit, and you feel your territory is being attacked (especially since you said he was grouchy to begin with). This cat then leaves before anything can get resolved (it usually takes days and days for cats to start to get along), and now you're back at square one. My cats get cranky at each other when one gets back from the vet because he smell weird. Ichi will smell foreign every time you bring him over, and that will upset Kermy every time. Also, once you do move in, Kermy will wonder why the 'visitor cat' is now in his house 24/7.

I would say your best bet is to shut Ichi in the room you will be staying in until him and Kermy can get used to eat other (BTW, this is after you have moved in). Long distance, intermittent introductions don't have a high chance of working due to WHY cats don't like newcomers (territorial reasons). Until that house is Ichy's territory, there's no point in upsetting Kermy.