A day in a SWE intern life is similar to that of any other full time software engineers. Google doesn't have a specific time for when you need to be in or out of the office. There are people who would come in at 11 AM, others at 8 AM. The time of arrival or departure is not really important because by the end of the day, all that matters is how much you get done on the project. For me, I'd come in to Google around 8:30 AM to get breakfast. After breakfast, I'd go to my workstation at around 9 AM. This is when I'd check my email and and my open Pull Requests (PRs) for comments (you would have a lot of PRs opened because the expectation is around one every day or one every two days). Once a week, I'd have a meeting with my host to update him on my project and see any evaluations he has for me. For any other days, I can start working right after I check my email. Usually, my productive work time is in a 20/80 or 40/60 split of producing new code vs. fixing current opened PR code depending how many PRs I have opened. At 11 AM, I have lunch with my team, then coffee, then back to work again. Around 5 PM or 6 PM is when I generally tap out. Around this time, my brain is typically fried. I'd just update in my personal journal what I have done for that day and what needs to be done the next day and browse some dank memes on the Google internal site. At 6:30 PM, I have dinner with any of my co-workers still hanging around. Usually I try to go home no later than 8 PM. But there are times when I'd feel rejuvenated after dinner and decided to stay back and work a bit more. The latest I have ever left the company was around 11 PM; however, that is more of an anomaly.
This is for me, different people have different schedules:
7:30 get in and use on site gym.
8:30 shower and then go to breakfast
9-9:30 get to desk (usually first on my team)
9:30-10 check emails, schedule, and read random news
10-12 Code. Usually had 2-3 bugs at a time
12-1 Eat with team
1-2:30 Code some more.
2:30-3 Break for some ping pong or 1:1 meeting, depending on the day
5:30-6:30 Usually just messing around with other interns until dinner time
6:30-7:30 Free dinner at the office
7:30-8:30 Interview prep with other interns (not every day)