Going back to office next month after 3 years WFH - my lab has never been home alone for more than an hour

So I got a new job and I start in 5 weeks. It's fully in-office, which I'm excited about, but I'm genuinely scared about what this means for my 3 year old lab, Huckleberry. I've been working from home since he was a puppy. The longest he's ever been alone is maybe an hour and a half when I run errands, and even then he's pretty whiny when I get back.

He's not destructive or anything, but he follows me from room to room all day. Like right now he's literally lying on my feet while I type this. He has zero concept of "mom leaves for 8 hours." I honestly don't know how this is going to go.

Has anyone gone through a transition like this? What did you do to prepare? I have 5 weeks before I start and I want to use that time wisely instead of just hoping for the best. Doggy daycare is an option but it's expensive and I'm not sure it's sustainable every single day.