When to tip!?

I think this depends on who you’re talking about. I think it’s fine to do this with major vendors like DJ, photographer, videographer, DOC, but I think people like hair and makeup artists and servers/bartenders who work for the caterer should be tipped the day of. I feel this is important because there would be no way to guarantee the servers would actually see the tip if just send it all to the caterer and if the makeup/hair people work for a salon, you don’t know what their process is on receiving tips.

I didn't tip my DJ til after the wedding because I didn't have cash so I just venmo him a gratuity fee

You could assign someone else to deal with handing out tips for you (or a person per vendor) if you can trust anyone.
Otherwise I'd say it's fine.

Is there someone you can trust to hand out the envelopes on the day of? This ensures everyone leaves with a good feeling at the end of the night.

I was able to get names of everyone who would be tipped (servers, bartenders, kitchen staff plus all major vendors) ahead of time and had envelopes prepared. It didn't take much effort to ensure that they were handed out, and it felt good not to have to worry about getting them out afterwards.

View Quoted Comment This! Unless you truly don't have bandwidth at the moment to plan it out or if you aren't going on your honeymoon right after and want to keep the wedding tasks going! Something nice about closing the book and enjoying your time rather than getting bogged down. We also sorted everything out before and had envelopes for each that my coordinator handed out.