As someone who has a startup with a multilingual web service (English / Japanese), I normally tell people considering translating their service to hold off as long as possible.

Going from have a unilingual website to a multilingual one slows everything down. Now whenever you make a change to one of the strings in your app, you need to wait to have it translated before you can deploy a new version.

Furthermore, merely translating your service isn't enough, you need to localise it. To do this, you (or someone else) needs to understand your target market. This isn't something you can outsource (cheaply at least).

Finally, adding another language to your application means you need to do customer support in that language. This means the founders can no longer do support themselves, and you'll need to rely on a third party instead.

Think carefully before going down the multilingual path.