Thank you written letter after phone informational interview?

Currently working in marketing, got set up with parent's friend of a friend who is a big time player in RE, the industry I'm trying to break into. Last Friday had a 20 minute phone call where he gave me some valuable insights on what I should do to break into the industry (his firm wasn't hiring he said). He told me to apply some of his advice to my resume and send it to him on Monday (today), he'd circle back and schedule a time to speak later this week. I stupidly forgot to send him a thank you email after we spoke and I shot him an updated resume this morning to which he confirmed looked okay then said we'd speak later this week. I've of course sent him a thank you and am now waiting for a follow-up from him later this week.

My question is a) is it likely he was pissed I forgot to send him a thank you email and/or handwritten letter? and b) should I go ahead and send him a handwritten letter or just let it go and continue to correspond with him (I think next meeting I get to speak more about myself and where I want to go, to which I'm optimistic he'll provide some contacts or just starting advice)? Thanks everyone