How to Treat Neutropenia With GCSF

When is there a circumstance where you do GCSF? Like it just seems so intuitive, let's just fix the neutropenia if this is such a problem. So like for example, it'd be like a lymphoma patient who's undergoing chemotherapy. You know that that person is going to be febrile neutropenic. The question then is then so when do you use GCSF and what's the data? And how do you peel them off in sequence, like the anti fungal, then the antibacterial?