I don't know where I got it, but somewhere early on, I printed out a block pattern - really just a grid, and I coloured in the squares with felt tip pens. Not necessarily the colours of my fabrics, just to use as a reminder, because I was aiming to make a trip round the world format. I assigned a particular print to each of my coloured blocks and that's how I kept track.
If you can't find a print out, perhaps a sheet of graph paper would help, just draw out a grid of 13 x 13 squares that you can colour in. I never thought about the tris for a few weeks, so I had to rearrange a few at the end, to avoid same fabrics being next to one another.
I also crossed off the completed ones on this grid too - I know I have the software, but a visual reminder was useful, I didn't always want to fire up the notebook just to see what colour I was supposed to be using.