Do I have to be in US physically for 3 months before applying N400 ?
I am having a valid N470 and will it not cover the above requirement?
Will the physical presence be re-calculated at the time of interview and
Oath? Both Physical Presence & Continuous Residence requirement have been met while applying N400.
Since I'll be working abroad with N470, I cannot stay in US to keep up with my physical presence even after filing N400.
I've been maintaining my residence in US by paying all bills-utility,phone etc for many years after I became LTP and have not changed my address since then.

You cannot file N-400 when you are physically outside US.

Is the reply on this thread by an attorney at GotcherLaw firm is wrong?
Applying for N-400 while working abroad on approved N-470 and REP - Immigration Information Discussion Forum (http://www.immigration-information.com/forums/forum/citizenship-and-retention-of-residency/naturalization-to-become-a-us-citizen/8534-applying-for-n-400-while-working-abroad-on-approved-n-470-and-rep)

My question was Can I file N400 once I came back to US from abroad provided both physical & continuous residency requirements are met? OR Do I have to stay in US and complete 3 months before filing N400? Note that I've an approved N470 and working from abroad for an US company.