0.5 mg of clonazepam no effect?

I just prescribed it today for the first time I was having real bad anxiety and panic attacks was getting very little sleep throughout the passed two nights. Went to ER since I won’t be able to see my psychiatrist till Monday. I took it at 2:30 pm PST and I just want to sleep and I can’t so it’s making me anxious. Anybody experienced the same? I also ate a meal since I’ve been eating very small portions before taking it. Or do I just need more time for it to kick in? Thanks