This is a mistaken question, fostered by the iniquitous habits of zoologists to earn their keep by classifying the snot out of anything they see. There is no such point--there is just a cloud of probability densities overhanging the question. The probability that a POPULATION will produce viable offspring with another POPULATION diminishes over time. There is not a biologically functional on/off switch that delineates the boundary crossing between species--the odds of success just keep diminishing with time since biological distinction occured.
WHAT? If macroevolution is true, then what I described must have occurred. (Now you are going to ask me for proof of that postulate.)