Too long, I reckon. But what has invariably has happened for me is that every time I wanted to order a PCB I add the components needed to a Google Spreadsheet which became my inventory list, but I wouldn't buy the PCB yet, I would just add it to a to-buy tab in my spreadsheet. Once I had a number of projects lined up (say, 20) I would buy the PCB's. I would tally up components from the spreadsheet and then put a big order in from suppliers and order more of the most common stuff. The bigger the list of projects that I add to the spreadsheet, the more I save. It was pretty time consuming setting up the spreadsheet but it saves me a lot of hassle. Doing it this way allows me to check my list to see if I have everything needed for a possible future build, which as long as it's not something with super rare, I could most likely build. The components that I most often need to reorder are pots, in/out jacks, and boxes because I just don't have the space.
