It is good you are worried. Goes to show you are in touch with reality. You should always keep an eye on what is going on in your market.

With regards to your plan and if you stick your plan. Please your plan as a startup is already out of date. As a startup you operate in a volatile and dynamic market place. As soon as you finished your plan it was out of date. A bit like a photograph. As soon as you took the snap things changed.

I think it would be wise to re visit your plan and update it as per the changes in the market place. It means you have to take you product to market earlier or in a different way. Depends.

If you are using beta testers for you service then this should be less of a concern. Hope you are.