Thank you for your feedback. The only certain dates that we have are for our official major Q releases which are scheduled for every 4 months. So our next major release will be in the middle of October.
Unfortunately we don't have strict schedule for the other builds but for sure we have at least one or two new versions every month. So if it is fine with you and your company you can schedule tests for new version every one or two months (and there certainly will be new version of JustDecompile to be tested at that time). Also if you need old and tested version you can always refer to the list with previous releases of JustDecompile here: http://www.telerik.com/account/your-products/product-versions/olderversions.aspx?pid=845
Please let me know if you have other questions or need further help.
the Telerik team