@domubpkm To be honest, we don't have an estimate. Here is what we're thinking: late this year and early next year we will release two batches of Pinephones geared toward enthusiasts happy to accept some potential sw shortcomings. Which OS, if any, these early phones will ship with is anyone's guess at the moment - its still early in the process. Then there will be a pause in production (kind-of-forced and not up to us; CNY - which realistically lasts over a month). This will give us an idea of the interest in the device and, as a bonus, also give some time for the software to mature as phones end-up in the users hands and people report issues (perhaps you guys even help devs out in the polishing process).
Once CNY storm blows over (late Feb/ early March 2020) we may decide to ship the phones cyclically changing the OS per batch (batch 1 UT; batch 2 LuneOs; batch 3 Maemo Leste, etc.,). We are even toying with the idea of having different color back-plates for each of the projects (UT = Orange/ KDE = Green etc.,) - perhaps even with a stamped-in logos, for when a batch ships with a particular OS. The default black back-plate will obviously always be there as an option. And I hope its clear to all that you can run whatever you desire on your PinePhone ... I'm sure someone will end up running XFCE just because its possible ;) So what the Phones ship with doesn't really matter all that much.
Anyways, we'll probably play it by the ear and see how it goes this years and early the next and take it from there. BTW, all I have written may not happen or may change - just letting you know what we're currently planning and thinking :)