I recently heard that the saints from the old testement were held in paradise until Jesus death then transfered to heaven. Any thoughts?
Not "held in Paradise" but held in Sheol/Hades -- the place of departed souls -- until the RESURRECTION OF CHRIST, at which time they were
taken to Paradise and are now in Paradise, which is in the third heaven.
Sheol was and is in the "lower parts of the earth" which I would interpret as the molten core of the earth, which science postulates. Until the resurrection of Christ, the righteous dead went to one "section" of Sheol (called "Abraham's bosom" in Luke 16) whereas the unrighteous dead went to another. There was a wide chasm between the two.
Since the resurrection, only the unrighteous dead go to Hades. The OT saints are in Heaven, which contains Paradise. These are evidently "the spirits of just men made perfect" (Heb. 12:23) whereas the NT saints are evidently "the general assembly and Church of the firstborn" (Heb. 12:22).
At the Great White Throne Judgment, the occupants of Hades will be resurrected -- the resurrection of damnation -- and will then be judged (Rev. 20:10-15). Thus "death and hell [Hades] will be ultimately cast into the Lake of Fire, which is located in "outer darkness" -- perhaps even outside our universe.
To those who are not saved, a word of warning: "It is appointed unto men ONCE to die, but after this THE JUDGMENT" (Heb. 9:27). There are no "second chances".
"Behold now is the accepted time, behold now is the day of salvation" (2 Cor. 6:2).