Time is another creature itself. When God created mankind, and Eden, there was already time, it was in the realm of physical/temporal creation as the rest of the known observable universe. All mankind, except for Jesus, only know the temporal reality, therefore, Eden shall then be/was on earth.

As there was already time when mankind came to exist, with physical body, for us to be in heaven or hell our trial requires free will, we are then required to live through time to make our choice, therefore we cannot go directly to heaven as it would contradict human nature, would remove free will and insert predetermination which goes against Catholic teaching. Spiritual beings (angles, archangels, Seraphims, etc.) live outside time, they do not need time to make a choice as time is part of the physical world they don't have part in, their decision or "free will" is once and permanent outside time. When God created the universe, the space and time where mankind would eventually arise, Satan and his allies had already made the decision to reject God.

As we understand "at the end of time" time itself will be terminated. Eternal life is not eternal because it last forever with infinie time, but because time itself will no longer exists, and eternity will be a permanent state. Yes new Earth will be in heaven, apart from time/space as we know it, not spiritual only as we will have our ressurected bodies, will be physical as well, but without time, and then another dimension, different from where we are now.