These chapters are from this month's issue and done as a measure to stop the gap from growing bigger. The release order for chapters 237-246 will be a bit random, though in case of this manga order doesn't really matter as most stories are self-contained anyway. Whether you read these or want to wait is up to you.
PS. Vol.20 of Chihayafuru will be worked on only after we finally release vol.4 of Mitsudomoe (it's some kind of cursed volume, I swear... it puts our typesetters out of comission one after another...)