Increase your withholding
If you are unable to fully fund your 401(k) now, you should try to increase your savings rate when you can. As you’ll get various raises and bonuses, you should consider redirecting a part of your pay increase to your 401(k) plan.
There are some 401(k) plans that will have an automatic escalation feature, which will further increase your savings rate over time, without additional action. Even the smallest savings increase will significantly improve your retirement finances. A worker who has $50,000 per year can save 1% more ($42 per month), but also earn 7% annual returns, which in the end means an extra $71,718 after 35 years.