A new Reddit account is on probation. You don't see this anywhere in the UI, but it's there. Reddit's filters look at karma, account age, and how you behave for the first few weeks, and they decide whether to show your posts to anyone at all.
Most founders find this out the bad way. They sign up, write a thoughtful post about their startup, hit publish, and watch it sit at one upvote forever. The post wasn't bad. The account was new.
Why warming up exists
Spammers are constant. The cheapest way to fight them is to make new accounts useless for a while. So Reddit auto-hides posts and comments from accounts that have low karma, no history, and look exactly like a bot would.
The fix is to look like a real person for two weeks. That's it. That's the whole game.
What a warm-up looks like
For the first ten days, comment more than you post. Pick three subs you already read and leave one or two thoughtful comments a day. Not promo. Not your link. Just real opinions, like you'd give a friend.
Aim for 100 comment karma before you post anything that has a stake in it. That number isn't magic, but it's the rough line where filters relax.
What to comment on
The easiest karma is on threads where someone is asking for help and you actually know the answer. Founder subs are full of these: pricing, hiring, churn, the same five questions on a loop. You've answered them in your head a hundred times. Type one out.
Avoid the pile-on threads where everyone is making the same joke. The karma there is fast but the filter notices.
Once you're warm
When you start posting, post one thing a week, not five. The filter is more forgiving once you have history, but it still notices when an account suddenly turns into a megaphone. Stay close to the cadence you used while warming up and you'll keep getting through.
The unglamorous truth is that the warm-up never really ends. Accounts that comment regularly post better than accounts that just post. So keep doing the thing that got you in.