Can I get all the rewards with the free pass and at the end buy the premium and get the premium rewards immediately or do I need to buy the pass first to start winning the premium rewards?

I know it's not that old, but I'm 30 now, and I tried to analyze why I'm hard stuck in silver. I played a lot of CSGO when I was younger, and I was pretty solid there, but now 10 years later in Valorant my aim is pretty rusty and slow comp...