Using a timing app is great because it also helps you determine the duration of the contraction. You have a contraction at 12 and it stops at 12:01 then another contraction starts at 12:03 that means your contractions are 3 minutes apart and 1 minute long
you just press the button when it starts and press it again when it ends. then it will times how long between each contraction as well automatically. it helped me alot!
5 minutes apart, 1 minute long and happening for 1 hr is usually real labor.