Working with a business guy to develop an application. I'm looking to have it complete say March-April, 2012. At what point do you involve beta testers -- a day before the expected launch? How does this all work?
Additionally, how do you get quality beta testers to test a new product? We currently have a splash page for people to subscribe to be notified when our product is launched... how else do you get more people to register to find out when the product is launched?
Building software is easy, finding uses is the hard part. You need to find your early adopters -- people who understand that its software in development, bugs and all. They are out there. I think you're on the right track with the sign-up. Put someone in charge of getting that page out there and driving sign-ups. Set a goal of 10, 100, or 1000 sign-ups and then keep the guy awake until that goal is reached. This is probably your business guy?
Next focus on getting your software to the point where its just barely usable, then email that list and ask them to start using it. Be honest and let them know its beta, its and its bugger. Most importantly, get feedback. Put mechanisms in place to get feedback. Either automatically or by asking outright. Iterate. Repeat.
The software you're building is probably wrong anyway, so the sooner you can get real live users using your app the sooner you can figure out whats wrong.
These aren't my ideas. And for a much more complete set of hows and whys I recommend #leanstartup
Depends what you're trying to do with beta testers.
If you're just trying to find bugs, you're going to want to get them involved around code complete date, but you're going to need to make sure to plan on doing a good chunk more development. The day before won't work if they find 5 critical bugs.
If you're trying to get feedback on the functionality/concept, get them involved as soon as you have a minimally viable product (#leanstartup, as Mike said). Set up a forum for them to post ideas and feedback (Disclaimer: I work for UserVoice, and we make such a forum) and start learning what sucks. Because a lot of it probably does (it does with every product).
GETTING beta testers is definitely a challenge. But you hopefully know your target market, and you should be able to find out where they hang out. Join a related group on LinkedIn, participate in an industry chat, comment on their blogs. Get to know them a little and then ask if they wouldn't mind giving you feedback. And give them a free account for life...they're saving your butt, so don't even think about turning around and charging them.
Hope that helps!