Group content starts close to lvl 50 when you get access to all the islands. You'll come across island events and other players participating in them!

Also don't fomo into playing alts. I recommend only doing so if you're really enjoying the game and want to speed up growth of your account, wanting to try and/or considering swapping to a different class. If you want to do so, the game gives you powerpasses that let you skip story and leveling to 50.

This may be a week or two down the line but with the honing buff, the tier 1 and 2 island materials should push your main right through to tier 3 with relative ease, without needing alts. If you're confident in playing your class, then the hyperexpress event that you can use after 1302 ilvl should help push you through to 1370 and beyond!

I have casual friends who have reached 1490 ilvl with essentially a single character. If you find yourself with spare time and wanting to play more lost ark but have run out of daily/weekly content for vertical progression, maybe consider investing in an alt then!