That's ten to the power of 18, therefore many more than the current population of earth. However, past members (of Earth) may also have had an opinion, so we must integrate the population over Earth's existance. Doing so we get about 100 billion, or 10 to the power of 11 (or 15 times the current population).
So when will that number of people have ever lived? We must make a function of world population, and solve it's integral for that population. Anyone wanna do that?
Edit: solved it with WA: it will take about 40 million years with whatever assumptions that it makes to reach that number of people. (www.wolframalpha.com/input/?i=cumulative+world+population+40000000)