Buy or Sell Now?

Hi im quite new to the game and I love it, I've read so many posts and watched so many guides in the past week that has helped me understand the game and how it works. I'm currently level one and nine games into the league. I was wondering if I should replace the players to begin to mold my team for next season as promotion is inevitable. I want to replace my second GK and buy one with 4stars & an ability (one-on-one stopper) and make him my first choice keeper. I also want to sell and replace my reserves as they're aging and not very good. According to some guides its better to buy after a week of competition and sell towards the end of the season, is this true? and if so, should I start buying players or wait until the first week of season two? I have pictures of my squad (Urban Legends), a picture of my finances (finance issues but will clear up after the cup & league bonuses, also currently upgrading stadium = more revenue), and also a picture of myself and the next best team in my league (Ramazan FC). So should I buy players now, or wait til next season as I have a decent squad? I've learned and began farming for tokens so you can see what i'm working with. (thanks to BridgeGoths Guide)

Do I aslo sell players that have bad form? (4* 21 y/o but has received 5's four games in a row)

A big thanks in advance.

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