I presume you're a PCA subscriber and have received your magazine by post before it's official release date of 20th (of each month).
I believe the competition is not officially open on the web site until the official release date of the mag.
OnePlus 5T review: Hands-on
Illustrator Andrés Lozano on his improv line work, brazen use of colours & hand sketching
iPhone X review
Comment envoyer gratuitement des gros fichiers ?