In my experiences, first one of the day might not be as good as you think. Unless the customer left his cum staint on/inside her body and she didn't clean properly or she got fucked like no tomorrow. Otherwise second of the day could be better if she cleaned herself properly inside out. Depends on when they wake up, sometimes they don't take a shower or brush teeth prior their first fuck. Especially if they use cheap shower products, they intend to reduce amounts of showers not only to protect their skin also save on bills. Plus they usually "perform" better after the warmup.
However there's always exception. I once booked a private sm session. After my arrival she told me I was her first customer in her new location. Later in our session she asked me to write her a good review in exchange for free session. I normally don't do that but I was in the middle of humping her pussy lips so I agreed her request without much consideration. Next time I saw her, after the even hotter session. When I put down the money after we finished, she immediately refused my payment because my "awesome review" (probably helped her a lot I assumed). But I already put down the money (even only 100 for 30min, felt more like 200 worth) and didn't want to be a cheap asshole again. Then she hold me like I was going to world war 3.