Low rent from the privious owner. How much should I raise the $$?

[Julie I.]

Hi! I purchased my first rental property this March, and there is an existing tenant. He has been living there for about five years, and currently, his 2-year lease is about to end in September. Since the previous owner didn't raise the rent for 2 years, his current rate($1200) is significantly lower than the market (renting around $1400 depending on rent.com and Zillow); I got the feeling that I can rent the place out for $1400, but many articles I read also advise not to raise the rent more than 8% which is $96 for me. Should I keep the raise around that range and ask for $1300 or increase more($1300-1380) to match the market? The tenant seems cool and paying rent on time so far; he said he wants to stay here. What would you do?