Interesting question. It's one we don't really have an answer to so I guess any answer is basically a personal original!
However, I think it was more than just a weekend.
We read in Patriarchs and Prophets " God saw that a Sabbath was essential for man, even in Paradise. He needed to lay aside his own interests and pursuits for one day of the seven, that he might more fully contemplate the works of God and meditate upon His power"
That seems to suggest to me, that they spent several Sabbaths laying aside their own pursuits and more fully contemplating God's works.
On page 50 she gives another clue that Adam engaged in work prior to his fall.
"In mental and physical activity Adam found one of the highest pleasures of his holy existence."
On page 51 of PP she gives another idea that Adam and Eve spent time learning about scientific wonders of creation.
Then if we turn to the book Great Controversy we can deduce a few more ideas on this matter:
"Adam is reinstated in his first dominion.
Transported with joy, he beholds the trees that were once his delight—the very trees whose fruit he himself had gathered in the days of his innocence and joy. He sees the vines that his own hands have trained, the very flowers that he once loved to care " GC548
From those descriptions it seems they were in the garden for a while. Long enough to explore a lot of the things God had made, long enough to train vines and probably design flower gardens.
But not thousands of years, probably not even a dozen years, For one thing they didn't have any children in Eden, yet once expelled they had many sons and daughters. Cain being their first child.