At what point do you do a chargeback for art?

I have been patient with an artist as they are busy and I understand that but it’s been also 3 months now and I have not heard from them in a month. They had told me early April they would send a rough sketch as they were busy with school (never received). I messaged them a week ago checking in and 4 days ago asking for a refund as I think it would be easier both for myself and them if they have not started yet and I need the money now anyways.

I don’t want to be rude either. But how long would you wait before taking action? I know they are a person and have their own life so I am hesitant to do a chargeback back. I am hoping to hear from them soon