Coming to Vegas next week . My question is what is an appropriate time to have an outcall to my hotel ? Does later in the evening or at night work best ?  

Works best for us! Don't over thing kit. Just have fun.

I myself like early evenings. 7 or 8 but am available as early as 12 noon up til 10pm.  
But everyone has their own preference, usually depends on what their day to day schedule is like in their private life.  

It's Vegas....   Pretty much any hour of the day works if it's within the ladies normal hours of availability.  Most will have a window of time on their websites.  Some are early morning people, some are early evening, some are night owls, and some are yeah whenever it works for you.  If you have a preferred time or special request just note it and they'll let you know if they can accommodate.  Best not to wait until last minute if you can avoid it, though my you might get lucky.  

I'm an early riser myself 4 am, so I love daytime dates! I can stay out late upon request in Las Vegas and party, like a rock star! 😆 Find a lady that tickles your fancy first. Many will charge extra for after dark hours.

I know most providers accept outcall bookings at all times of the night- it’s good to have a few in mind just in case she may not be available or what I love to do — arrange a pre booking/ pre discussed time range

Some ladies are set between certain times  

I happen to be in town next week too and to be honest my experience is that as long as we have providers dress discreetly and if you're in the mood for a mom next door. We could meet anywhere and no one would  suspect anything. Especially girls like me who are low volume and aren't seeing all the time. I'm only  going to be here two weeks out of the month the first week of March and the last week of March. Check me out if you haven't found someone already. There really are some great girls here in Vegas. You just have to know where to look.

Anytime works for me . I’m your girl
 . Take a look at my reviews and get a hold of me .

I prefer daytime/early evening. But can prepare myself in advance for a later visit. Especially love dinner dates and shows. Not really a super late night person. Prefer my mornings!!! Am always up early, if you know what I mean!