"Plagron Bat-mix is a mix of the finest, carefully selected types of peat. It contains various types of fibre and perlite which results in a lightness and oxygen level you have come to expect only of Plagron quality potting soil.
The abundant presence of unique Plagron worm compost ensures vigorous plant growth and increased water retention. The main nutrient in Plagron Bat-mix is bat manure (Bat-guano). Bat manure is naturally rich in phosphorus and potassium, guaranteeing abundant growth.
Plagron Bat-mix contains sufficient nutrients to meet all the needs of the plant throughout the complete cycle. Only under closely controlled conditions can Bat-Guano be processed into the top quality Plagron product.
Attention! Water well, allowing the water to seep through, before use. Do not add any fertilizer for the first 6 weeks."
I'd say after 6 weeks, use nutes according to nute labeling or less.