Hello folks

I just planted my first 2 cannabis seeds 5 days ago, and I’m wondering when can I start using General Hydroponics trio of nutrients and calmag? I planted them in 2 small pots, and used some humus to help the roots grow. The person that sold me the humus told me to not use nutrients right now, only ph balanced water, because it may kill the humus and it would lose its purpose... is this true? He told me to start using nutrients until after switching to a bigger pot

Otherwise, can somebody point me towards the right direction in regards to using nutrients during the first few weeks of plant life?

I planted in mostly coco coir