During your registration you have indicated that no have a VAT number yet. After this, you can try out one shift if freelancing is something that would suit you.
In this case, the invoice of your shift will not show any VAT as you are not an entrepreneur yet in the eyes of the Belastingdienst (Tax Authority). You do not have to declare this shift at the ‘omzetbelastingaangifte’ (VAT Tax Declaration).
Please note: in all cases you do have to declare your taxes at the ‘inkomstenbelastingaangifte’ (Yearly Tax Declaration).
Exception: Were you in posession of a VAT number the application of your first shift and was this not added to your profile yet? In that case it is possible that it is not legal that the VAT was not on your invoice. So it is not about the moment that you were working, but at the moment you were applying to the shift. In this case, please contact firstname.lastname@example.org so that we can help you fix this.