Yes they do.
Seeking approval for a development is only part of the equation. They also have to line up contractors, tradespeople, financing etc., which can all take considerable time.
Sometimes developers work with city planners behind the scenes ahead of time so that the PAC approval process is essentially a fait accompli (like with the 20 Record Street project), and construction begins almost immediately after approval is given.
You just know that Lafford already had all his ducks in a row before having his project rubber stamped. Most other times it will take 12-30 months following approval to break ground.