Upgrade Machine or Grinder [500€]

Hi Everyone!

I got into the hobby earlier this year with a manual grinder (Timemore C3 Esp Pro) and a Delonghi Dedica.

Usually, I buy dark roast beans and make 2 lattes a day and I'm getting ok results, especially after taking the time to warm up the machine (1 blank shot and 2 pre-infusion shots), portafilter and cup.

I have a budget of 500 euro to spend this month on Black Friday and trying to decide whether to upgrade the grinder or the machine. What would make more impact in getting good coffee and consistent results? The grinder or machine upgrade?

EDIT: I use a bottomless portafilter, unpressurized basket, WDT, tamper with calibrated sprint, puck screen. Heat settings adjusted and I pull the shots as per Kaffeemacher settings (way better shots since I started doing that). I also warm up the portafilter before pulling the shot. I've been trying with different options but lately what's been working for me is 16g in 35g out in 28-30s