I think a lot would depend on how much experience these people have and how exacting they want the finished project. If they are non-sewers/non-quilters, it could take months to get them up to par to make a quilt that would be sufficient to sell/auction/whatever. If the people you are going to be teaching know nothing about sewing machines, you'll need to tack on time you will spend fixing the messes they make and possibly to do a lot of the work yourself as they will not be able to and/or won't want to do it once they realize what is involved.. IMO, you're a brave soul to consider taking this on.