For early 401k withdrawals, do you have to withhold taxes at time of withdrawal, or can you just make estimated payments before the tax year is over?

I made an early withdrawal on my 401k in early 2017.  I didn't withhold taxes, because I didn't earn much income in 2016 (lived off savings as I left my salary job in 2015 to start new business).  Should I still make estimated tax payments to reach 20% withholding throughout the year?  Or will my tax be lower given my low income level in 2016?