Cramer, who has always viewed Canopy as a best-in-class among the cannabis companies, had cautioned as recently as Wednesday, the day Canada legalized marijuana for recreational use, that he would not pull the trigger yet.
But two days later, Cramer said, "It is time to buy" Canopy, adding he feels the stock is "done going down" after last week's high, making it an attractive investment.
Shares of Canopy opened on Friday about 2 percent higher at nearly $50 each.
Canopy hit a new 52-week high above $59 during the trading day on Oct. 17, adding to a 14.2 percent gain the prior day after announcing a takeover of U.S.-based hemp company Evergreen. But by the Oct. 17 close, Canopy fell 6.8 percent to about $53.
In the Wall Street frenzy for Canadian pot stocks in advance of legalization, Canopy shares have gained more than 400 percent in the past 12 months.
With this latest investment and execution of some warrants, Constellation said its stake in Canopy will become 38 percent. The Corona and Modelo maker also received an opportunity over the next three years to buy up to 139.7 million in new Canopy shares, which represents up to $5 billion in additional funding. If Constellation utilizes those warrants, it could raise its total stake in Canopy to more than 50 percent.
"One day Constellation may be 50 percent of its market cap," Cramer said on Friday.
Cramer's charitable trust does not own any Canopy shares. It sold Constellation Brands before the August announcement regarding Canopy.