"Get off after two stops!"
Translation:İki durak sonra in!
In other words, when describing something compared to a specific event (e.g. "after 2 o'clock" or "after the bus reaches the second stop") the ablative is used, whereas when describing something relative to a quantized measure of time (e.g. "2 hours later"/"after 2 hours" or "two bus stops later"/"after two bus stops") the ablative is not used.
With that in mind, when trying to determine whether or not the ablative should be used it is not a bad idea to compare it to English, because this exact same distinction is made in English by strictly using "later" over "after" whenever possible: you would use "after" only when describing something compared to a specific event; otherwise, "after" is not used.