Not sure why previous posts have been expired, but I have signed up recently and received my voucher in the email on the same day.
Voucher expires after 30 days
A $10 voucher issued to a new IKEA Family member to redeem on any valid purchases either instore or online within 30 days from the date an IKEA Family member joined the IKEA Family Club. The voucher can only be redeemed once by the eligible member. This voucher cannot be used in conjunction with any other voucher.
Redemption of $10 reward
To redeem the $10 voucher instore, members must either present the original voucher email to an IKEA staff at checkout to scan, or scan the barcode from the voucher email at the self-serve checkout. Alternatively, to redeem online, enter the coupon code in the field box before you proceed to checkout.
The member’s IKEA Family membership must be scanned at point of redemption.
There is a minimum spend of AU $10 to redeem this voucher and can only be used in a single purchase. The $10 voucher must be redeemed within 30 days from the date an IKEA Family member joined the IKEA Family Club.
The redemption cannot be made when purchasing an IKEA gift card.
Full t&c's here