Exit A of the Botanic Gardens MRT station (yellow Circle line CC19 / blue Downtown line DT9).
Meet at the top of the escalators, outside.
Careful - this is NOT the Botanic Gardens entrance on Napier Rd. This is on the Bukit Timah Rd side of the gardens.
The tour ends at the Beauty World Centre (with plenty of local food and drinks) and I'll take you down to the MRT station if you're headed back by train (blue Downtown line, DT5).