I always about a 1/4-1/2 yard more of each color than I think I will need so that I don't stress about miscuts.
When I have cut every thing first, I've liked it. However, I sometimes either misread or miscut pieces so I usually hesitate to cut everything at once. I generally take it one section or one block series at a time and cut just what I need for that part of the project. That gives me some leeway in correcting my cuts or changing up the fabric if I don't like the outcome.

That said, I have a friend who is much more anal than myself and she is very methodical. She cuts everything first and spends a lot of time laying out fabrics and making sure her cuts are perfect. She labels and organizes everything and when she sits down to sew, she is very efficient. That works for her and she does beautiful work.

I am not that efficient and enjoy the process and the ability to be creative and switch out fabrics throughout the project. I like doing my own thing so, figure out what works for you... .

All good ideas. From now -on I will make a sample block. I usually cut out most of the pieces at once and pray that I don't make a mistake and need more fabric.

Edited to add, I will make a sample block from SCRAP FABRIC as so many have suggested.

I would make a sample block and if it worked out okay I would cut all the block fabrics. I do not cut the borders until I am ready to put them on as the difference in seam allowances when figured over the whole surface may make a difference in the border length. OR you can go ahead and cut the borders allowing some extra for the difference in seam allowances. I like to measure the quilt before I cut just to be sure. I don't like to have to piece on an extra inch! NOTE: Even though you think you are sewing a good 1/4 inch seam you can be off just a tad and it's good to check it occasionally with several rulers to be sure!

I have a fractured vertebra in my lower back, so can only stand for short periods of time. I started sitting and cutting about 5 years ago. I have an adjustable table for better leverage, and fold my fabric so that the WOF is 11". Using the June Tailor Shape Cut is also a big time saver.

definantly cut the whole quilt pieces that way you can change the color combination if you want-and quickly run to the store if needed if you aren't using you stash scraps!!!!!!

I usually cut out the whole thing and label carefully. Seems to work better for me this way.