Hello MMM community!

First of all, this is my first forum post - I discovered MMM several weeks ago and it was a revelation. The concept of maximizing your savings rate hit me like a brick - DUH! and now I'm seriously excited to start building my 'stash.

If this question has been answered elsewhere on the forum, I apologize and would appreciate a link.

I spent some time building a Google sheets model that will allow me to effectively track my spending. I'm now trying to build a longer term model that can let me play with potential FIRE timelines based on income, savings rate, 401k etc.

In this case, my question is: are there any good rules of thumb for modeling 401K growth? I contribute 5% of my salary, and my employer provides 5% match. Should I then assume a 5% return? In any given year, is it accurate to simply take:

(Current 401K * 1.05) + ((monthly deposit * 12)*1.05) ?

Or does that not take into account the fact that the January monthly deposit has been providing returns for 11 months by year end, and I should factor that in?

Greatly appreciate any feedback. So happy I found this community!