Marsu, I have worked in product development for many years (including Panasonic for a spell) and there are typically four phases of product development - (1) model or mock up (2), prototype (3), pre-production model, and (4) final production model. The model is usually in CAD and clay, and the prototype is usually hand made with existing parts from existing models along with new components. There are typically numerous prototypes as various parts are completed (e.g. sensor, body, firmware, etc.). Once that is approved, the most difficult and lengthy part begins, which is preparing a model for production. This consists of testing of the prototypes, tooling for the parts, and most challenging, updates to the assembly line (or even construction of a new line) along with all of the QA/QC processes that have to be developed/modified.
A pre-production model is one that has "rolled" off the assembly line, but is still rough around the edges and ready for final testing and optimization. At this point, it's about 90% or so of the final product, but some items like firmware, grips, branding (logos) and such may not be complete. Pre-pro models also go through iterations and are frequently at 100% before manufacturing capacity and/or marketing campaigns are ready.
So, to answer your question, it depends on the final testing and how much the line has to be adjusted. If the changes are minor, the product might come out right away, if they are major, it will be much longer. Given Canon's extensive experience in DSLR manufacturing, I'm thinking this is a final "shake down" of the product from pros before the August announcement. They are a good sign, unlike the patents that often registered simply to protect a design and never intended for manufacture.
That's probably WAY more than you wanted to know
The stages are design, prototype, beta, pilot, pre-production, then mass production.
Most field users are likely testing the product at pilot stage. These methods are currently in use at the company I'm with. Time line? it depends on how fast the engineers can debug all field issues. Also, how fast can purchasing dept. can get raw material with their suppliers.
Take a look at 1Dx announce date and release date