Now is the time!
I was just reading and replying to another post, and it reminded me it might be a good idea to repeat myself here specifically regarding using a fixed length line set up. To me, this is the best time of the year to be out fishing, so if you are new to tenkara, or would like to get someone else started, there is literally no time like the present -
At least in my neck of the woods, the next 6 weeks or so are a great time to take new people out to catch their first fish on a fly. The bugs are active on the water, and so are the fish.
The waters I fish have great populations of caddis flies, which I've come to appreciate, especially for getting a new person into catching fish. Fishing caddis "patterns" on top seem to be ideal for the new fisher. The flies are fairly easy to see on the water, and it's ok (actually often preferred) if they are presented with a less than perfect dead drift float.
The strikes are aggressive so folks don't miss the fact that a fish took a swipe.Even if the beginner doesn't hook them all, the fact that they are seeing fish keeps the interest level high.
Maybe the nicest thing about it is after spending 15 minutes or so getting them started, they know enough to catch a fish or two. So they can more or less be left alone allowing you to catch a few fish yourself.
I'd encourage if you know someone who'd like to catch a fish on the fly, now's a great time to get them out fishing.
From a purely selfish perspective, I find the fish gods tend to smile upon those who take some time to help out others in a fishy way.