Cyrus, 19, got engaged to Hemsworth on May 31 after a three-year relationship, reported Ace Showbiz.
"My advice is just take it easy. If you can be engaged for a while I'm sure that's really nice, plan everything slow and take your first couple of years just to really hang out together and enjoy it," Underwood said.
Underwood married to ice hockey star Mike Fisher in July 2010, just six months after he proposed.
"For me, planning, I wish we could have been engaged a little bit longer but our schedules were like, 'We can get married this day', so that's what we had."