T.S.
Hi D.,
I can totally empathize with you on this. Moving is tough for kids, even when we KNOW it is the right move for our families.
For us, 20 minutes is nothing... still basically the same place, but for kids it's huge: new school, new neighbors, new ice cream shop, etc.
We moved to Maryland from California two years ago when my son was 5. Here's what we found helpful that'd I'd recommend:
1) If you can get to the new place at least a few weeks before school starts, do it. Call the school and find out what daycare/aftercare/rec-center most kids attend... then call that place and get them in to daycamp for the last two weeks of summer. They'll get a chance to meet the kids they'll see at school when it's all FUN. They'll walk into school on the first day already knowing several friends.
2) Make finding their new faves a priority. If they love walking to the donut shop on Saturday mornings (that was our thing) get a version of that going RIGHT AWAY, so they start to have things they love in the new neighborhood.
3) Go to the park, library, pool, etc. in the NEW neighborhood. Since it's only 20 minutes it would be easy to pack up and drive back to their old stomping grounds... which you can do sometimes... but while they adjust to the new place, help them get to know it by sticking close to your new home. Just like with daycamp, if you stay close to your new house, they're likely to meet kids they'll see at school.
4) Call the school. Since they aren't entering Kindergarten, there's probably no kind of "welcome" event or orientation for them. Ask the school if there is a day this summer you and the boys could come by and tour the campus. They'll be a lot more comfortable day one if they know where the bathroom is, how to get from class to the cafeteria, their lunch # etc.
5) Remember that this is the RIGHT move for your whole family. Keep it positive (not apologetic) and they'll do fine.