I don't really have a feeling how long these things take but this is a lot different from bolting on something like a new front wing. I've read that some teams would end up having to change the gearbox to accommodate it for example, and bits and pieces like that make me think we won't see it elsewhere any time soon. The top teams in particular have tightly packaged rear ends without much room to easily make such a significant change.
I was just speculating on the timeline but, unless other teams had already considered that design, there's not long until the first race and they already have a lot on their plate... especially the Renault teams! The first four races are all fly aways so I think it would be amazing if anyone has it before Spain in mid May.
We'll see I guess. The other teams might run simulations and decide the aerodynamic benefit is too small to be worth the hassle, it's impossible to say how it will all turn out right now.