I became navigator on a mate's yacht during a 4- 1/2 hour race last Sunday when his plotter packed up and he found that he had not renewed his Navionics subscription for his iPad. Out came the chart and parallel rules and it was only a few moments' (satisfying) work to give him an EP, based on DR since the last island and a depth contour, and a clearing bearing past the next reef. It made up for blocking his view of the compass while my dyslexic mind figured out which way to wrap the sheet on the Genoa winch - every time we tacked!
So, the answer to the OP's "when?" is "Four days ago".
I keep my charts in a transparent waterproof chart holder so I can read them but I don’t write on them. Instead, I draw a plotting sheet for my vicinity and use that for all notes, plots, bearings, course, speed etc. A3 size sheets work well. The lat/long dimensions are simple to draw with a protractor. One sheet to cover no more than 2 degrees of latitude.