Well, I thought I was going to upload a picture of my ciabatta, but something in the translation from camera to computer went awry so there is no picture and the bread is all gone!
I put the biga in the fridge after leaving it out for 16 hours and left it there three days before I had time to make the ciabatta. Made the ciabatta following Rose’s recipe in the Bread Bible
and it came out superb. The only thing I would have done different is to not do the 5 minutes in the oven with the door open at the end of baking. The crust got a bit too crisp for my taste.
Otherwise it worked out great.
Thanks for all your help!