Not really long.. I mean, time is relative. Years ago I played around with 3D Studio Max, but that was really only "playing around", nothing to show. The "real start", with blender, happened about two months ago. Of course with the "Blender Noob to Pro" guide.
The things I made are rather simple, even the "terrain map" if you know how - basically modified boxes or grids. I also often notice that lack of "know how" when creating something new, then I feel like doing the most complicated steps to accomplish the simplest thing

, but I'm sure that this comes with experience over time.
The books took some hours, most of the time spent for preparing the texture and later for the UV-mapping.
The hammock is nothing more but a plane with moved vertices and a hand-drawn "threads" texture with transparent background. Probably some few hours.
The terrain with skybox, some days, most of the time spent for collecting and preparing textures (this was actually more trying around and see what I can get), but it's not finished.. I just can't get a nice skybox working.. it's easy to show the "nice part" of the skybox in a screenshot but moving reveals all its flaws

For the tutorial terrain I had the textures prepared already. So, without skybox or any objects - a freeform-terrain (without a plan to follow) probably less than an hour. Well, at least for that I got some kind of "good workflow".
@Nikodemus: I pondered about helping one of the teams indeed, but at the moment I've quite some stress here and there, thus prefer to not load another duty onto my shoulders. And being in such a team, you better take it serious like a job to get things done. I'd probably only delay
