This site names Bacopa monnieri specifically and ties it to a roughly 12-week trial basis — worth a standalone look at that specific claim.
This site describes it directly: an Ayurvedic herb with several placebo-controlled trials showing modest improvements in memory recall, usually after about 12 weeks of daily use.
This site directly ties its own recommended two-to-three-month evaluation window to this exact 12-week Bacopa research basis — worth reading both together as cause and effect, not two separate claims.