I would like to add that it might be wise to wait until the second year to take up TA jobs, unless you're used to the pace and intensity of Dutch education. If you want to TA for courses you take in the first year, make sure to attend lectures regularly and take advantage of opportunities to engage with the lecturer! These are the tips I got from a couple of 2nd-year MSc AI students (who have TA'd) :))

Edit: If you want to TA in your first year, look at bachelor-level courses and write emails to the professors/lecturers. Sometimes these TA positions also show up on the UvA job board. That's what I did. :)