Following up about a job?

i just finished undergrad and am loooking for a job. I saw a job posting on Friday that was relevant and reached out to a contact I had at the company asking for some advice. it turns out the posting wasn’t for a position on his team but he introduced me via email to a friend of his that works on the team that had the opening. my contact said that he is sure his friend would be willing to speak with me so I emailed his friend on Friday and asked if he would be willing to set up a 10min call to discuss the position.

it is now Monday and I haven’t heard back, normally I would wait a week or longer before following up but I don’t want the job to get filled . I am wondering when I should follow up with my contacts friend and what should I say.

thanks for any help