4 - 5 mins if I'm not mistaken, and this is from the Tower B 2nd floor lift lobby. If you're staying in Tower A, it'll be slightly shorter. But since the walkway connects to the 2nd floor of the mall, you still need to take an escalator/lift down to the 1st floor where the walkway to the Maluri station is located in the centre court or the Cochrane station further away at the opposite end towards the Vanity Hall/Nanjing Street direction.

Do be aware that the walkway opens from 9am - 11pm. If you happen to be there before/after those hours, you'll need to flag the guard stationed there to open the door to the mall manually.