To what extent is it OK to entertain fantasies whilst engaging in NoFap?

I've been on hardmode for about a month now. Without concious thought my mind frequently conjures up sexual fantasies. Is this OK? Can I expect these lascivious daydreams to subside eventually? They occur most commonly in the mornings, immediately after i wake up whilst i'm still in a hypnagogic daze.

Despite this, I can certainly attest to reaping all the benefits of NoFap that are often talked about on here. Thanks.