How to request timeoff immedialy after onboarding new company?

Congrats! Both on the new job and the marriage 😊

First, I recommend letting people know now that you're taking time off. I assume you have talked to the hiring manager at least once during the interview loop. If you have their contact info, reach out to them directly. Otherwise have the recruiter pass them a message.

In general, earlier is better when it comes to quality, open communication. The failure mode you want to avoid is that the manager has some big plans for you right after you start which are then rug pulled last minute due to your 2 week leave. That would leave a bitter taste in everyone's mouths to start off your journey - Not good.

As for the communication itself, just be honest and don't overthink it. Marriage is definitely a top priority personal life event (and hopefully a once-in-a-lifetime type thing 😉), so this isn't something they can really block (and if they do, that's a red flag for your long-term future at the company).

For general communication tips, check this out: Effective Communication For Engineers

Have a great wedding!