Lag times on lagers are typical 30-32 hours at the longest. As mentioned above by JA that pitch rates are critical. By doing what Ben does, pitching and fermenting at higher temperatures, you can get by with less yeast (it's also under pressure). Lower temperatures require more yeast. Depending on yeast strains, temperature and pitch rate, the lag can be as short as 12 hours and as long as 30 hours. Anything above 30 hours makes me nervous.
I would suggest in the future to use dry yeast, specifically 34/70. Pitching warm (62F) you can use 1-2 packets, pitch cold (48F) 2-3 packets. More yeast isn't going to hurt anything and it will provide some insurance. The other advantage of dry yeast is the need for oxygen is pretty much eliminated. As JA mentioned, lagers require a lot of oxygen at pitch when using a liquid yeast, more than ales and even more when under-pitched as in your situation. The reasons for this are a little complicated, but as long as you know this rules, you should be fine.
Edit: 34/70 typically has a longer lag time in my experience, closer to 24-30 hours, even with a massive pitch. So don't panic if you don't get 12 hours out of it. WLP833 is a shorter lag time, 12-18 hours, but it's liquid and requires 12-15ppm of oxygen at pitch.