It's not just what you suggest, that it makes it harder to get money. The other impact is that you don't have time optimize for best person, you have to optimize for getting cash fast. Also, it is much easier to get to know a person when you aren't asking for money. We had a similar approach as Posterous and are really happy we took the time to get to know VCs before raising money.
Right - I think that's actually the most valuable lesson in your post. Start making friends a year or more before you raise.
There may be a small caveat - it's worth debating this because I'm not sure I'm right but I'll throw it out anyway: Some investors like a fresh face with a fresh idea. If you become a groupie and hang out at every single event for a year before you raise, you may be less attractive to investors than a fresh face with the same traction and idea. Not sure if this is true but just a thought.
I partially agree with your caveat. In our case we went to almost zero events, all of our meetings were face-to-face with a single firm. After that we stayed in touch and gave updates on our progress. This also let them get comfortable with our ability to work together and execute on a product. We were also able to show more and more traction over time.
Investors will get tired of you if you are raising money for a long time. Once you decide you are raising, get all your meetings done as quick as possible, hopefully in only a couple of weeks.
It may not need to be a year. We started these discussions in June and started raising in September. They key is just before you need money.
really means
"If you appear to need money, you are too late."
and restated the way one of my investors once put it
"If you have the stench of death about you it's impossible to raise."
If you don't need money, don't raise.