Speaking to the Daily Telegraph, Coleman said: "You can't come in and change everything all at once, you have to be very careful.
"I understand that if it's not working in six or 12 months there'll be another guy in charge, but I think the chairman [Ray Ranson] has a long-term, realistic view.
"This club is capable of going to the Premier League and staying there.
"Without being disrespectful to Fulham, you could only do so much there, and I really should have left a little earlier."