Well this is what I do,
for the first couple of weeks I do abservations, a few longer, planned ones during free play and small, incidental ones, when a child does something new or interesting. There is no set amount or time. Don't write it if it's not helpful.
Then I look at the next steps for each obs. What can I do to reinforce what the child knows and move them on a bit? Write down a few activities/ideas.
When I've got a good few, I transfer the next steps ideas onto a PLOD (there not called this anymore but it's what I'm used too, can't think of new name) so basically, under each EYFS heading I have a list of goals and activities. I also write at the bottom, which are my responsablity to carry out, and which need support at home.
After that, I have each child's PLOD infront of me and transfer those ideas onto a big planning sheet that goes up on my wall.
All activities that come from the obs are written in green. This covers the EYFS, meeting the child's specific needs and interests.
I then look at it and see if there is anything I'm not covering. Or something new I would like to introduce to the children. This is written in blue on the planning sheet and covers "proving a balanced curriculum".
All obs, photos and examples of the children's work is kept in the learning diary.
Once a term or something I fill in the development passport but I think that's something we only do in our area, not sure.
It sounds like an awful lot doesn't it? I found it really hard to get my head around it. I feel like I write down every process that I just do naturally, without realising, as a mother.
Hope this helps. I've just discovered that it helps to write it down or explain it someone else!