I think that's the plan!
Yep, you're right. A TLC press release (and I think the Oprah website, too) said the new season starts in May. May is 'sweeps' month for tv networks and I'm not surprised TLC would be bringing J&K+8 back then. The replacement 'Table for 12' is contracted for 10 episodes, so they'll have enough time to air them and then bring back J&K.
I sure wish they'd taken more family time off cause they'll be busy filming season 5 all thru the summer. The twins will get out of school just in time to start working full time again.