level 1 slots first, then max gem mine, then max slots

That's my advice anyway

I honestly don't remember what I did, but my advice would be to do the gem mine first.  That increases your supply of gems faster, and it quickly pays for itself.

gem production need  around 1 year just to start make some profit. training camp just useless peace of content.

Spend your diamonds only for market slots & energy bottles during corresponding events&tornaments.

Strongly disagree.

It;s a *LONG*-term investment to be sure, but it eventually pays off. Which imo is all the more reason to start on it as early as possible.

Ash did a vid sometime in the last year where he workled it out that a maxed sparring pit gives enough xp to level up enough chickens to end up with 5 5*s a week

Now, that also depends on how often throughout the day you're able to log into raid .

What I do is have several sets of chickens in progress at any given time. While I'm online and activiely playing, ill have whoever is the lowest levels and needs the shortest time to level up in the pit.

If ii'm doing stuff irl but can pop in for a minute or 2 every couple of hours, i can set mid level champs that will take a awhile longer

And when I go to bed I set higher level champs close to ranking up.

In other words, i have very little downtime where a spot in my sparring pit isn;t actively providing xp

Gem mine > unlock slots IMO.  Ive never upgraded my pit spots and don't think i would notice much of a difference if I had.