Yes, you can track your IF hours right in the diary, although it goes to a max of 24 hours. If you forget to start it, you can go in manually and adjust the time/date settings. You can also set what your goal is (up to 24 hours) and see how much time has elapsed to know whether you've hit that goal. If you're not seeing that feature in your diary, maybe it's a premium feature.

I'm not sure about on here but there is a google play app called body fast that I use to use in the beginning. Also, for less hassle, I often would just set the timer on my phone or computer. You can save the timer and you don't have to put much thought into it.