Evolve Treecko now or wait for CD?

Sceptile with leaf blade is one of the best pvp pokemons. Better with LB imo.

Also, with a CD you will probably get a couple of good trekkos so no real loss evolving now

At the 2500 CP cap, leafblade is better.

However, both meganium and venasaur with frenzyplant out DPS and out TDO leafblade sceptile.

If you want a good grass attacker, I would pick either of the other 2 CD starters, however if you want your team to have sceptile, leafblade is the better move.

Do you see yourself using this Sceptile for raids and gyms as well?

If I were you'd I'd wait for the Community Day, especially since you seem to care about ensuring that this particular Treecko gets his best moves possible.

There's a great chance that Sceptile gets Frenzy Plant this year, however I'm suspicious of the appearance of Blaze Kick and Muddy Water in the game master. Both attacks were a sort of trademark to Blaziken and Swampert respectively, and I think Niantic may have actually anticipated how good these Gen 3 starters are predicted to be post-Community Day and might have a different attack in store for the three of them for Community Day (although it's not clear what that would mean for Sceptile in particular, as his Gen 3 trademark was Leaf Blade, which is obviously already in the game).

However, that wandering-speculation on my three favorite Pokemon aside, I'd still wait for Community Day and see what Sceptile gets. If it's a great exclusive attack, then you get it and you win. If it's a great attack that also compliments Leaf Blade, then you get it and you can unlock Sceptile's (inexpensive) 2nd move to also get Leaf Blade and you double-win. And if for some reason it's a lame exclusive move, then you just wait until after it's gone and evolve for Leaf Blade and you still win (although a few months later than you might've liked.)