I cut as I go.

I cut it all up front. measure twice and mark rulers. But this is after I have used scraps to make the block. This way I know if I cut right and I like the block.

I usually get it all cut out a couple of days before I start to sew as I find that part tedious, and I label all the pieces

I cut everything but the sashing and boarders I'm famous for changing my mind on those two things.

I also cut as I go. I have shoulder tendonitis and can only cut for so long. So I figure by doing a some cutting and then some sewing it is a little easier on the body.

I usually make a block to make sure that everything fits and looks good. Then I cut some and sew some. That way I don't get bored and it seems like a different project with each step. I usually buy my borders when I'm ready to put them on. I rarely buy the borders when I get the rest of the fabric unless I want to match the borders with the sashing. I like to buy my quilts in pieces--give me a good excuse to go to the quilt shop.
Sue

I have done both. But, recently discovered that after I cut everything out and THEN made a practice block that I did not like it and wanted to go in another direction. I learned I will always make a practice block first. I am still working on that quilt and I think that is what put me in a funk of not wanting to quilt. I have made it work and have almost got the top completed. Will finish tonight. I have had to make myself complete this job. Would have just thrown it to the scrap heap if it wasn't a special quilt I am making for my husband using a military type theme. After the top is done I will put it aside and finish a couple of others before going back. But, lesson learned about cutting everything out at once!

Most of the time I don't cut it all at once.

I usually make one block to see how it will work and then cut all the fabric. I too have had to go back and buy more fabric.
and I have also had the unfortunate experience of waiting too long and the fabric isn't available anymore.

I always cut every thing except the borders and back, then I can just sew when I feel like it without having to stop and cut more.