Ok so speck is due in December 2012? So your DH realistically be looking for work at the start of 2013? So saying that got something and relocated it would be 12 months maximum as I'm assuming you would want to relocated yourself and settled in before your DS starts school in 2014? You would probably want to be there for transition time in Oct/Nov 2013.

That is probably a max of 9 months apart if you think about it like that. I think I could cope with that especially if he came back say once a month. If you do a schedule and plan it I think it would be doable and I wouldn't want to disrupt DS more than once in a transition. He will be disrupted with a school start anyway so will it be worse to have a big move all at once with relocating, school and new support, or a series of disruptions?