Given today's tooling, I would probably have started later, but at the time it took us long enough to get a good Enterprise product put together that having started quite early gave us a reasonable timeline to enter the Enterprise market with a competent offering. I don't regret our timing at all.

The biggest problem with getting into Enterprise too early is that it will slow you down. With today's great tooling (e.g. Replicated) you can accelerate your technical solution, but you'll still be faced with the overall added complexity of an expanded deployment base, differing customer requirements, more complex (and demanding) support requests, long sales cycles requiring dedicated sales people, and a lot more. All of this to say, sometimes its better to keep velocity up so you can accomplish more with the goal of getting Enterprises to come to YOU.