Partial preterism says all eschatological events except Jesus' return have already occurred. However, Matt. 24:29-31 show this is wrong.
Matt. 24:29 “Immediately after the tribulation of those days the sun will be darkened, and the moon will not give its light; the stars will fall from heaven, and the powers of the heavens will be shaken. 30 Then the sign of the Son of Man will appear in heaven, and then all the tribes of the earth will mourn, and they will see the Son of Man coming on the clouds of heaven with power and great glory. 31 And He will send His angels with a great sound of a trumpet, and they will gather together His elect from the four winds, from one end of heaven to the other.
There can be no denying of "immediately". This shows the whole partial pret idea is incorrect. (As is full preterism, of course!)