Trial Tip?

Hi ladies!


Going to get my hair and makeup trial done today! So...the place I am going to is in Twin Cities Bridal magazines for being a really good place and very reputable. Their hair and makeup are $100 for each for trial. So it’s $200 total.
The actual cost for each will be more on my wedding day.
My question is this (and I think I know the answer but want to be sure of the amount): How much do you tip, if anything, at a trial?
Do I tip $20 each? Is that being cheap? Or do I not tip at all because it’s only the trial and you paid for the trial service...the big tip will be on the big day?
For some reason the thought of only tipping them a 20 each today for the trial...seems cheap 😫
Any thoughts on percentage?
Thanks!
Jessica