How long should I wait before following up with a senior contact who left me on read?

Im a second-year finance student networking for a winter co-op at a large institutional investor. I connected with someone senior on the team through another mutual contact who is already advocating for me, and the senior person suggested we do a two-step connect. First, a phone call, and then an in-person coffee later this month. We've been texting to schedule the call. He confirmed weekdays after 6 pm work for him, so I proposed two days that we could chat, and he said either or works.I followed up the next morning to nail down which day and he read it but hasn't responded in over 24 hours. Is this normal for someone at his level? Should I send another message tomorrow asking if tonight works or is that too pushy? Don't want to come across as needy but also don't want to lose the opportunity.