idk abt new portal but old portal I did purchase agv, and I didn't got 8k. voucher. Then I raised manual credit points to customer care in april. They told me why there wasn't auto credit of 8k points is coz it was a new card so it wasn't linked to rewards portal yet.
For safe side, I'll suggest you to do the trxn next month, so that hopefully by then card would be linked to idfc rewards portal. Till this month end, make sure you open rewards portal 1-2 times so rewards portal syncs with the new card.
I am telling this based on experience of old portal. If someone has experience of new portal with brand new idfc wealth card (like they got the digital card not physical card delivered yet in last 1-2 days), they can update us if there was instant 8k points or not.