On the first sign change of $\theta(x) - x$
  Let $\theta(x) = \sum_{p\leq x} \log p$. We show that $\theta(x)<x$ for $2<x< 1.39\cdot 10^{17}$. We also show that there is an $x<\exp(727.951332668)$ for which $\theta(x) >x.$ 
Dave Platt and Tim Trudgian
math.NT