What Would You Do?

I am going through the process of getting my head round Hamish starting preschool next year.  The big question is what two days should I put him in?
Points to consider;
• Preschool's rules are that for two days you can only pick from Monday-Tuesday or Thursday-Friday
• Jack goes Monday-Tuesday-Wednesday
• Hamish knows a lot of the kids on the days Jack goes
• If he goes the same days as Jack, I will get 2 days where I am child less and can study/work/actually get stuff done
• Will Hamish interfere with Jacks preschool experience?
• Will Jack interfere with Hamish's preschool experience?
• Will Jack enjoy having Hamish at preschool?
• Will Hamish settle easier with Jack being there?
• Having them in separate days means that I will get 2 days alone with Jack

At this time of night I think that's it. In a perfect world I'd love them to cross over for only one day, but its not an option, so its all or nothing.  So I'm calling for ideas, ideals and any other points I haven't thought of to help me make sense of this tangle of ideas.