Air conditioning in new construction - What preparations?

And one more question that is burning under my nails...

We would like to equip our new building with air conditioning in the near future. We are currently still in the shell construction phase and are considering what is best to prepare now to save costs.

It is a semi-detached house with ground floor/upper floor and attic as a pitched roof, facing southwest. To the left of the house is the garage, then comes the play street.
I imagined a split unit. Where is the best place to position it? On the roof facing east? Or on the south side on the garage / in the shade of the garage?
The living room, the rooms on the upper floor, and the attic are to be cooled. It is questionable whether each room on the upper floor needs a unit (2x children's rooms and bedroom including dressing room) or if it can be solved differently.
What should be done now if possible and what can simply be made up for later?

Looking forward to your tips.

You need 2x refrigerant lines, 1x condensate drain, and 1x power/control cable from the outdoor unit to every point where an indoor unit is to be installed. It is best to plan and install this in advance. Afterwards, it is not always optimal, especially regarding the appearance.

Where is the best place for the outdoor unit? Yes, shade is good. Preferably not too high since the units are heavy, and you might even need a crane if it has to go on a house roof. A garage roof sounds quite good.

Also, consider the lengths of the refrigerant lines. You need to check the technical data of the outdoor unit for this. What total lengths are allowed and what height differences. Every meter costs money, and noticeably so.

Our outdoor unit is on the carport roof, a man carried it up there, I thought it couldn't be that heavy. We have 1 split unit for the entire upper floor, 1 for the office, and 1 for living/dining/cooking. According to the consultant, it is enough to cool down the upper floor in the evening, as houses are very well insulated nowadays.

We usually have 2 hot weeks a year. With shading, it never gets hotter than 23 to 24 degrees. See air conditioning as a waste of money.

We usually have 2 hot weeks a year. With shading, it never gets hotter than 23 to 24 degrees. I see air conditioning as a waste of money

I can’t confirm that, we ourselves have had an air conditioner in the old building since this year. It is a massive gain in comfort, which particularly affects the sleeping climate. In addition, you can also wonderfully heat with the air conditioner down to about 7°C. What needs to be prepared has already been wonderfully described by mycraft. If necessary, you should also plan thoroughly whether you can manage with just one outdoor unit or whether it is better to position two. Because the refrigerant line is also not exactly cheap and should not be too long, although I think 15 m is possible with ours (possibly also depending on the height difference). With what you’re describing, you quickly come up to 5 indoor units, and then you reach the limit with a (normal) outdoor unit. Above all, the outdoor units then become increasingly expensive, so in the end two units might be more sensible. Regarding the weight, we have a 4-split system and the outdoor unit weighs a solid 71 kg, carried by two men on the roof and lifted through the skylight by four.

It is also very different what people perceive as "too hot." For me, significantly more than 2 weeks a year are too hot, and the trend is rather increasing. My husband is from Queensland, where practically every house has air conditioning, and he wanted that for the house here as well; it was practically his only real demand for what the house must have.