Summoning sickness (CR 302.6) prevents a creature from attacking or using activated abilities that include the tap symbol (T) or untap symbol (Q) in their cost, unless the creature has haste or has been under your control since your most recent turn began.
Convoke (CR 702.50) lets you tap creatures you control as you cast a spell to reduce its cost. Tapping a creature for convoke is part of paying the spell's cost, and CR 702.50b specifically states that creatures tapped this way must be able to be tapped — meaning the summoning sickness restriction still applies.
Vigilance (CR 702.20) simply means that a creature doesn't tap when it attacks (CR 702.20b). It says nothing about summoning sickness or activated ability restrictions. It does not grant any ability to use the tap symbol while under summoning sickness.
So a creature with summoning sickness and vigilance still cannot be tapped for convoke, because vigilance does not remove the CR 302.6 restriction on tapping creatures with summoning sickness for costs.
Example: You play a 2/2 creature with vigilance on your first turn. On that same turn you try to cast a spell with convoke, hoping to tap your 2/2 to help pay. You cannot — it has summoning sickness and vigilance provides no exception. Next turn, with summoning sickness gone, you could tap it freely for convoke.
Unofficial fan resource — not affiliated with or endorsed by Wizards of the Coast. Answers are AI-generated estimates grounded in the Comprehensive Rules and are not a substitute for an official judge. Verify anything match-critical.