This research, conducted in an upper post-primary Computer Science classroom, explores how students learning Python engaged with ChatGPT. A key output of the study was the co-creation, with students, of heuristics (guiding principles) to support the ethical and effective use of ChatGPT while learning to program. These include: (i) a general set to support learning in contexts where generative AI is available, and (ii) the SAV framework (Specify the problem, Ask again, Verify the output), a specific set for engaging with ChatGPT. These heuristics are presented as working prototypes.