Eric Ebron’s welcome-to-the-NFL moment came early. Ebron was on the field running routes, learning the offense with some of the Lions veterans this week when tight ends coach Ron Prince told his new rookie to take a rep with the first team. Ebron lined up, looked to his side and couldn’t believe he was standing next to Calvin Johnson. “It’s fun,” Ebron said. “When you’re lining up beside Calvin Johnson and he asks you, he be like, ‘Are you good?’ And I’m like, ‘Yeah, I’m good,’ but you’re still shaking because you’re lining up beside Calvin Johnson. But it’s fun, man. It’s fun to touch bases with people like that and understand where they’re from and their personalities, not just think that they’re superhuman but they’re human, too.” Ebron was the star attraction on Day 1 of rookie minicamp Friday, though reporters only saw a quick glimpse of him blocking, taking part in a special-teams drill and doing some primal position work during the 20 minutes of open practice. The 10th overall pick in last week’s draft, Ebron is expected to play an immediate and significant role in what the Lions believe will be a diverse and high-powered offense. First, though, the North Carolina product has to learn a playbook he admitted is “challenging” already. “Of course your head is swimming,” Ebron said. “I think I had a migraine 30 seconds after we started going over the playbook. But it’s very fun. It’s very fun to learn new thingsh and once you grasp it you can do it full speed, you understand why they’re coaching you so far.” Ebron and the rest of the Lions’ eight-man draft class, plus 12 undrafted free agents, 23 tryout players and a handful of practice-squad holdovers, went through about 2 hours of drills Friday and have two more practices today and Sunday. Coach Jim Caldwell said the goal is to inundate the group with the playbook so that by the time training camp rolls around in July they’ll be caught up enough to contribute.