Not make start time a mandatory field

When setting up a wedding photoshoot dashboard it requires that I put a start time with the date, but 90% of my clients don’t know the exact start time yet, so I had to something there and explain it to every one of the client, as it confuses them just before they are about to sign the contract 🤣
Would u be able to change the settings to make the start time not a mandatory field when entering the date?