The ever excellent CBInsights just released new data on the time between rounds. As you can see from the chart above year to date in 2014 the median time between seed and Series A has been 349 days and that’s been reasonably consistent over the last couple of years. If the median time is just under a year then in the spirit of planning for the worst and hoping for the best this data suggests that reckoning on making your seed round last 12-18 months is the way to go.
Thinking about our portfolio and other companies I have seen recently in the UK I would estimate that over here the median time from Seed to Series A is slightly longer than this, maybe just over a year. That would make sense given that the volume of capital in the market is lower and the competition between investors is less intense. (The good news is that the a number of new funds have come to market recently, including Google Ventures and Mosaic Ventures.)
For UK companies then, I would advise reckoning on 12 months as a minimum. Some companies do better than that, but that takes luck and it isn’t wise to plan on being lucky.
All that said, within reason more runway is better and if you can get extra cash at an acceptable dilution it’s usually worth doing. Important caveat: if you do raise a large seed round don’t ramp the burn too much before you’ve found a repeatable business model.
On a side note, in a bubble times between rounds usually drops, but we’re not seeing that in the chart above, or in times between later rounds.