I have done this, will pick out the pattern I would be using (usually one that is used for pre-cuts) then pick out the fabric and cut into the what ever is required for the item I'm making, i.e. layer cakes, jelly rolls or what ever. Find that it saves me a lot of time when I do set down to sew as everything is pre-cut to what the pattern calls for. Probably waste fabric but to me it is worth it to set down and be able to use the pattern without thinking about how to cut it. Hope this helps.