This is going to sound harsh, but when I hear people in their 20s fixating on not being published by a certain age, my first thought is that they likely aren't taking the work seriously enough. This isn't a status game. It's not how old you are, it's when your work is ready.

Fall in love with a project, finish it, give it time, start other projects, revise the older thing, revise it again, get feedback on finished work, keep moving, keep trying. Read endlessly & voraciously. Love the work itself. Write the book you want to read. That's the only way.