On the topic of designing 100% before launching. It is different for everyone. I have had numerous chats with Paul Carpenter about that very topic and it really boils down to the creator. Should a first timer do it absolutely not. (Wait a minute, you did it jerk) Your right I did do it but I also had almost 12 years of design and package design experience before coming to the table.
I remember when Lance Miller came to KS with his Actuators project. He'd had a very successful release of his Bicycle Gargoyles through Diavoli and wanted to be a little more independent this time around. However, he had relatively little of the art done going into the first project for the color deck, which resulted in him being several weeks off of his scheduled delivery date. So here's a case of an experienced designer who shouldn't have done what you, Jackson, already did!
I think it really does boil down to the individual and their capabilities. When I was in high school, I had a serious aptitude for computer programming. In my Computer Math III class, I was not challenged in the least by the work that was being assigned, so I spend most of my class time tackling my own side projects to challenge myself - and I played some video games! One day, the teacher gave us an assignment in the last five minutes of class, explained the entire assignment top to bottom, and when the bell rang, I handed him a piece of paper. He said, "What's this?" I replied, "The homework assignment - it's already done." I never studied for a single test, including the final, and never scored less than 100.
And it was the worst thing that I and the school could ever have done, leaving me in that class. Other students saw what I was doing, saw I was getting great grades and tried emulating what I did to some degree, or at least the fun parts like playing the video games. As a result, their scores suffered, some close to the point of failing. What was as easy as breathing for me was a lot more challenging for them.
Getting back to designing a KS deck project, it's probably a good idea to have somewhere between 50% and 95% of the work completed, depending on your level of expertise in design. Not 100%, but close to it - if you're 100% done, you have no room to account for changes your backers may find desirable. You really have to know yourself to do that, and many first timers won't have the experience under their belts to know themselves well enough to gauge this properly, especially those first timers who never worked in design before - a young kid who toys around and knows a little about Photoshop and almost nothing about deadlines.
If you're nearly completed when you launch, don't blow the whole wad at once - use reveals. It's what some designers do on their decks - a percentage of their art is completed before the project, but they don't reveal it on the outset and leave it at that. They tease it out over the course of the campaign, particularly as new works are completed leading to that 100% mark so when the project is done, they've got it pretty well locked down and are either within a few days of submitting art to USPC or are completely ready, no need to wait.
I've heard of people wanting to hold off on showing an entire deck because they're paying someone else to do the design work and they don't want to pay the artist yet for the full job because they don't want to risk their cash on a project that might fail.. These projects tend to flounder - you have some fantastic vision in your head of what you want, but couldn't get it down on paper or into a computer hard drive. If you have the funds, you have to show people what their getting - only a handful of backers (cough-GALAXY-cough-CARDS-cough-THREE-cough) would be willing to shell out on a deck that they haven't even seen the full work for yet. That also holds true for an artist that isn't close enough to finished by project's end, leaving more work yet to do.
NOW, LADIES AND GENTS, it's been a lovely tangent, but can we get back to the topic, please? It's a lovely topic, too, right? Feel free to make a new topic on this subject in the design board - it would generate a lively discussion, I think.