@ Zebedee
Good point! where does it say (in the Quran) that Hell/Pardise existed before the trumpet is blown?
Q. 26:90-1
And the Garden will be brought near for those who ward off (evil). And hell will appear plainly to the erring.Q. 81:12-3
[81:12]
when Hell shall be set blazing, when Paradise shall be brought near...Hm, these verses don't really seem to say that heaven and hell are created on the Last Day, although you might be able to interpret 81:12 like that, but I don't know the exact meaning of the word used.
There's no statement to definitively prove your contention, that paradise and hell are created on the eschaton, but let's look at some ahadith.
Bukhari obviously. Maybe you'd accept some of his hadith

Volume 4, Book 54, Number 462:
Narrated Ibn Abbas:
The Prophet said, "On the night of my Ascent to the Heaven, I saw Moses who was a tall brown curly-haired man as if he was one of the men of Shan'awa tribe, and I saw Jesus, a man of medium height and moderate complexion inclined to the red and white colors and of lank hair. I also saw Malik, the gate-keeper of the (Hell) Fire and Ad-Dajjal amongst the signs which Allah showed me." (The Prophet then recited the Holy Verse): "So be not you in doubt of meeting him' when you met Moses during the night of Mi'raj over the heavens" (32.23)Volume 4, Book 54, Number 474:
Narrated Anas bin Malik:
The Prophet said, "There is a tree in Paradise (which is so big and huge that) if a rider travels in its shade for one hundred years, he would not be able to cross it."Volume 4, Book 54, Number 482:
Narrated Abu Huraira:
Allah's Apostle said, "The (Hell) Fire complained to its Lord saying, 'O my Lord! My different parts eat up each other.' So, He allowed it to take two breaths, one in the winter and the other in summer, and this is the reason for the severe heat and the bitter cold you find (in weather)."Volume 4, Book 54, Number 483:
Narrated Abu Jamra Ad-Dabi:
I used to sit with Ibn 'Abbas in Mecca. Once I had a fever and he said (to me), "Cool your fever with Zam-zam water, for Allah's Apostle said: 'It, (the Fever) is
from the heat of the (Hell) Fire; so, cool it with water (or Zam-zam water)."Volume 4, Book 54, Number 484:
Narrated Rafi bin Khadij:
I heard the Prophet saying, "Fever is from the heat of the (Hell) Fire; so cool it with water." Volume 4, Book 54, Number 485:
Narrated Aisha:
The Prophet said, "Fever is from the heat of the (Hell) Fire, so cool it with water." Volume 4, Book 54, Number 486:
Narrated Ibn 'Umar:
The Prophet said, "Fever is from the heat of the (Hell) Fire; so abate fever with water."Etc., etc. There's also the hadith in which Paradise and Fire dispute with each other, but I can't think of the reference now.
Aside from that, in the Qur'an there's the thing with Muhammad being taken to Paradise and shown the Lote tree and all the rest of it.
Q. 53:13-8
Indeed, he saw him another time by the Lote-Tree of the Boundary nigh which is the Garden of the Refuge, when there covered the Lote-Tree that which covered; his eye swerved not; nor swept astray. Indeed, he saw one of the greatest signs of his Lord.Seems to me that these verses do say that at least paradise exists presently, and that Muhammad saw it, or parts of it.