My last 3 lagers I have pitched one can of Imperial Organic Yeast with no starter. Had visible and vigorous airlock activity within 12 hours. I have been very happy with the results. Cans were fresh (less than two weeks from "canned on" date.)
In this case I think you are fine not making a starter. In any case where the yeast has some age on it a starter would be very beneficial for a lager or use a good dry strain. 34/70 makes a fine lager.
I will add, if you are pitching a lager yeast at fermentation temps (say 48-52) and getting activity 12-24 hours later, you know you pitched enough yeast. If you are having to pitch warm to get the yeast started then cool down to fermentation temps you aren't necessarily pitching enough yeast.