Thanks to good performances, he qualified for the 2017 PDC World Youth Championship and reached the Second round on his debut.
The following year, Nentjes took part in the Q-School in Hildesheim but was unable to win a Tour Card.
Nentjes faced Kim Huybrechts in the first round, in a very close match he eventually lost 2–3.
[2] Despite some signs of promise, Nentjes finished 88th on the PDC Order of Merit after his first two years as a professional.
However, he won a two-year Tour Card straight back at European Q School at the start of 2021, beating Boris Koltsov 6–5 in the final on day two.