If it's ready for release on Android then nothing is lost by releasing it now. In fact it might bring the dependency on Facebook into play faster and it's good to get to 'No' quickly. [1]

As a general observation, many successful apps have a website in addition to a presence in the app stores. So it makes sense to assume you'll be building a web page anyway. For an app like yours, it's probably easier to test and iterate core logic on a webpage than in a mobile device.

Whether it makes sense to build a web page at this point requires looking at the risk of the second dependency versus the cost of building a page and that's a business decision for your business.

[1]: http://venturebeat.com/2013/06/26/get-to-no-as-fast-as-you-c...