When you’re working on your product, you’ve got some beta testers, it looks shit but you’re making progress, and you’ve a huge list of things you want to do, it’s easy to put off marketing.
“We’re not ready for loads of customers yet”
“We’ve too much to do to be marketing”
“Let’s wait till the product is great, then marketing will be easier”
The truth is, marketing is really hard. It takes time to work, it can be hard to know when it is working, and you don’t see instant results so it doesn’t feel very productive.
Getting started earlier, and doing a little as you go along is, I think, a much better strategy than waiting till you launch. It gives you time to learn about what works and what doesn’t, it let’s you learn about the process and get better at it, and it gives your marketing time to work.
Market the hell out of the app man!
EDIT: What I meant to say is that as you put it marketing is very hard (I know, that´s what I do) so don´t narrow it down. Go for it, right now!
Might I suggest putting an extra "Request an invite" between "Let me know when Float is ready for Xero" and the extra form data to get early access? It's a great idea to collect meaningful information in exchange for earlier access, but you might be losing people who just want to drop their email and go by having them scroll over the much longer form.