"For, behold, in those days, and in that time, when I shall bring again the captivity of Judah and Jerusalem, I will also gather all nations, and will bring them down into the valley of Jehoshaphat, and will plead with them there for my people and for my heritage Israel, whom they have scattered among the nations, and parted my land."-Joel 3:1-2 KJV
Are we end the end times, is Joel fulfilled?
No.
In Chapter 2, this prophecy is conditional.
"Who knoweth if he will return and repent, and leave a blessing behind him; even a meat offering and a drink offering unto the LORD your God?"-Joel 2:14 KJV
And it was for a certain time
"weep between the porch and the altar,"-Joel 2:17(C) KJV
So not fully fulfilled and it doesn't seem to be so, but the Spiritual prophecies of this Book are still fulfilled.
"Gather the people, sanctify the congregation, assemble the elders, gather the children, and those that suck the breasts: let the bridegroom go forth of his chamber, and the bride out of her closet."-Joel 2:16 KJV
"And ye shall know that I am in the midst of Israel, and that I am the LORD your God, and none else: and my people shall never be ashamed. And it shall come to pass afterward, that I will pour out my spirit upon all flesh; and your sons and your daughters shall prophesy, your old men shall dream dreams, your young men shall see visions: And also upon the servants and upon the handmaids in those days will I pour out my spirit. And I will shew wonders in the heavens and in the earth, blood, and fire, and pillars of smoke. The sun shall be turned into darkness, and the moon into blood, before the great and the terrible day of the LORD come. And it shall come to pass, that whosoever shall call on the name of the LORD shall be delivered: for in mount Zion and in Jerusalem shall be deliverance, as the LORD hath said, and in the remnant whom the LORD shall call."-Joel 2:27-32 KJV
"So shall ye know that I am the LORD your God dwelling in Zion, my holy mountain:"-Joel 3:17(a-b) KJV