Assuming that firing Jim Comey, the FBI Director, does not erode Donald Trump's loyal base, soon he could no longer have the lowest approval rating during each day of his presidency when compared to other modern (post WWII) presidents.
On May 15, 2017 or day 116 of the Trump presidency, has an approval rating of 40.5%.
On day 123, Gerald Ford had an approval rating of 39.9%, so Trump's may be higher on May 22, 2017.
On day 131, Bill Clinton had an approval rating of 36.8%, so Trump's will probably be higher on May 30, 2017.
Of course, Trump and his supporters will claim that his popularity is comparable to other presidents, while everyone else notes how unpopular he actually is and has been.
Trump is likely to have the highest disapproval during each day of his first year (if not impeached by a Republican House and removed by a Republican Senate) and may have the highest disapproval during each day of his first term (if not impeached by a Democratic House and removed by a Democratic Senate).