I believe you should add a way to collect these rewards from previous season. wihtout waiting for season to start. allow new players to get the quests done and receive them 

And why should players get the rewards for playing a season that they never played? The previous players put in the time and had to wait for each season to get each item. I see no reason why newer players should be treated any differently (and I speak as someone who missed the first season). Newer players will be able to get the rewards by playing through the seasons just like the players who have played through every season.

And since this is the last season that they'll be handing out a new capotia reward, no one will be falling further behind, and if you're behind, you'll be able to get the ones your missing via future seasons, whereas those who already have them won't be able to get any further PEN capotia rewards. So, in that sense, anyone who's behind will be able to get more out of the next season than the people who aren't behind will.