Not a gent but replying anyways cause I think it needs to be said 😆
There is no ‘best time’. It’s completely subjective to preference for everyone - including the provider & the client. Literally anything besides time of day can influence a booking, it’s more nuanced than just earliest/first to latest/last.
I recommend asking the provider you’re wanting to book with since they will know what time of day they prefer to book/works for them. For example, I absolutely do not like morning appointments as I am not a morning person but I’ve had amazing morning bookings as well. I prefer noon to around 4pm, but that doesn’t mean my best bookings are within that time frame either. So, ask the provider & suggest your preferred time and if they are willing to accommodate it