You are being rude. If he/she is a first time fish keeper you can and will make mistakes. So you've never made mistakes in the past then?
Back to the OP, Pets at home are VERY bad for advice, to them cycling a tank is leaving it for 3 days and that's it. I have gone as far as reporting my local store to head office for their bad care and for selling me diseased fish, advice and snotty attitudes to customers.
I went in the other day and told them right out I had reported them and the answer I got back was "well we know how to look after the fish and we are very knowledgeable" looks like it doesn't it?
I believe we live and learn, you've learned to never ever listen to pet stores such as pets at home, do research, go to forums and you'll be fine. Good luck.