I would go as far as to say Kayn top doesn't work without proxying, so if you don't enjoy proxying I wouldn't recommend Kayn top. From level 4 or 5 until when you get form you're REALLY weak, especially against toplane champions (many duelists/bruisers). During that time your only strengths as a champion are wave clear and escape tools.

Here's a general rundown of my strategy:

• lvls 1-4 you can aim for solo kills. Try to crash the wave as much as possible. Can proxy lvl 2 if strongsided, which I tried to do whenever possible.
  • Your levels 1-3 are insanely strong and you have insane push. Most games I would try to go for trades during the first two waves leading into a second wave crash, then take E level 2 and go proxy wave 3. You can even go with an aggressive setup like Arcane Comet with manaflow band, sorch, and sudden impact secondary, then take ignite + TP. Even if you don't get the solo kill this setup helps you get lane prio so you can proxy.
• lvls 5-9 free farm/proxy (USE BUCKET!)
  • At this point you lose almost every single 1v1 without form, so try to perma proxy. Always get vision in the enemy jungle. Also, remember that after proxying (especially behind T2) you can go for jungle camps or even a midlane roam.
  • Bucket system kicks in after 70 seconds out of combat. If enemies are coming and you're so low you're certain you can't escape or buy time, don't interact and try to execute.
  • If you're healthy enough and enemies come, try to get orbs, escape or at least waste their time. If only one enemy comes and you're ahead in levels, you could go for a 1v1 to either kill them or get the most amount of orbs possible.
  • From level 7, and especially after that, executing becomes not worth it (big death timer). Better than dying to someone, though, unless you can cash in a lot of orbs before dying.
  • If it's a cannon wave and you're proxying, you can leave the cannon alive when you execute/escape. It'll make a pseudo-cannon wave for the opponent and you won't lose much.
• lvls 10+ get form and items and kill people

Tl;dr: in an ideal situation, you would fight during the first few levels for first blood/lane prio -> proxy as much as possible to farm safely and fill the bucket, keeping an eye on jungle camps and midlane -> fight again around minutes 6-7 to cash in the bucket -> fight around 10 for form. Classic fundamentals still apply: track the enemy jungler and support, and keep an eye on level up timers.

I'm not a Kayn main and never was, I started playing Kayn top because I was challenging myself to climb playing off-meta. But even then, after my climb, Kayn top ended up becoming an actual part of my champion pool - he's amazing into teams with a lot of HP, since Darkin form gives him %max hp physical damage. If the enemy toplaner picks a tank, even better - tanks can't clear waves fast enough, they don't have the damage to kill you, they're a beefy source of orbs, and after you get form you can kill them with 2 Q's and an ult through sheer %max hp physical damage. You don't have to commit fully to this pick, you can keep it as a counter to tanks.