Only ever owned one .177 rifle (S200) and I zeroed that at 35yds which seemed to work well.
For now, until you are able to Chrono the rifle................ 25 to 35 is a good starting point mate.
When you are able to Crono the rifle and work out an accurate average FTLB you can start to narrow things down a bit more with Chairgun.
Having Avg ftld+ pellet type and weight + reticle choice + Magnification you would prefer........feed all of that into Chairgun and you can play with the variables to find a good overall set up after looking at what Chairgun suggests.......and tweak from there by using the preselected tools.
Near perfect results can be achieved if you have the ability to alter the rifles power output with very small adjustments mostly.
Chairgun works best with generic Hawke scope reticles mostly.
I don't tend to use Chairgun these days....though I do Chrono the rifles to check the output.
With a brand new rifle, the first thing I do is clean the barrel to get rid of grease used to store the rifles after production.....check all the stock screws etc.
Take the woodwork off and clean/oil grease....then reapply.....OCD or what
Set the trigger weight and blade angle if possible.
Carefully make sure my scope mounting and eye relief are on the money..........no cant of the scope (use level and string)............ and repeatable head position/eye relief.
I lay prone behind the rifle.....with both eyes closed.....then shoulder the rifle........feel for a comfortable head/cheek rest.....then open my eyes......If I have an edge to edge clear sight picture I'm happy.....even happier if I can repeat that process time and time again without moving head position and eye relief at all.
Make a decision whether I need or could benefit from an adjustable/thinner/or thicker butt pad for reach.
Then off to the range to try some pellets and achieve the best MPI results to find what the barrel of the rifle likes.......normally start at 10yds and then move back to my prefered zero range. ..........I only use domed pellets.
Also, the head size of a pellet can make a huge difference turning good groups into excellent ones.......as long as you do your bit.
Once I have the zero range and pellet selected I will start to move back with the distances in 5 yd increments (using a rangefinder or tape measure.....never guesswork)
Map the scope out to the maximum range I feel comfortable and confident shooting game at.......further for target work and playing.
Make a tidy and neat drawing of the scope ret and my aim points and tape it to the rifle so I always have the reference.
As far as scopes go.........I much prefer something in the 4x to 16x range (eyes are knackered now) for hunting and target work with the option of an illuminated reticle and adjustable Parallax.
All of the above waffle is how I like to do things.........not suggesting it will suit everyone though
Good luck with the zeroing Matt hope you have a good day out there and get the results you want
Look forward to seeing how you get on mate