Starting the trail alone at a young age can be daunting, but it's really exciting once you get there. I started a thru-hike this past summer at 18 as a solo male hiker. I started on June 23rd during all the fires and the temperature in Denver was 105F. I ran into multiple thru-hikers and spent some time hiking with most of them. I ended up hurting my back about a mile from the end of segment 5 by not stopping to rearrange my pack when something was digging into my back. After a 4 day rest in Breckenridge, I tried to continue with segment 7, but my back was a no-go and I ended up turning around and bailing back at Breckenridge. I still haven't decided whether or not I'm coming back this Summer to have another go at it, so I don't know about partnering up, but you can PM me if you have any questions about planning or what the experience is like from a young hiker's perspective. Barring any weather oddities like this past Summer (heatwave - little water in the first few segments), I believe mid to late June is the best time to start the trail as long as the snow has melted. That's when the seasonal streams are most likely to be active and the bugs and monsoonal storms are not as bothersome.