Get pen and paper
Switching from whatever you were doing into getting ready to write breaks your concentration, and starting up again is often the hardest part. The visual support below holds the direction through that shift.
♂Get pen and paper
A hand holding a blue pen writes on a sheet of paper on a table.
♂Get pen and paper
A person leans forward and writes with a blue pen on a stack of paper.
About this visual support
The shift into writing begins not at the paper but in the head. The child was just inside something else, perhaps a game or a screen, and now has to leave it, fetch pen and paper, and on top of that find the way back to the thought that needs to go down on the page. That first step is where many get stuck, not the writing itself.
Visual support helps by giving the transition a visible direction. With cards for finish what I am doing, fetch a pen, fetch paper and sit down, the child does not have to hold the whole switch in mind at once. Each picture points to the next, and the move from sofa to desk becomes a string of small actions instead of one big leap.
A concrete tip: keep the paper and pen in one fixed, always the same, spot and let a picture show that exact place, so searching does not eat up the little starting energy the child has. When the physical spot and the picture match, getting going is quicker. To make the transition look the same every time, you can save the sequence in Routined and bring it up when it is time to write.