I've been LAing for others for over 10 years now. I used to 'save' time slots for people. But I can't tell you the number of times they didn't get me the top when they said they would (or ever, in some cases!). Meanwhile I had told other customers that I couldn't do their quilt until X weeks later, because I had all these quilts 'penciled in' on my schedule. Then I was sitting there with no quilts to do and no way to pay my bills.
I no longer put a quilt on the schedule until it's in my shop. My customers know if they have a quilt with a deadline (such as baby, wedding, graduation, etc.) I will do my best to get it done in time, as long as they get it to me in a reasonable time frame (no, you can't bring it to me the day before you need it! It normally takes 9 months to make a baby, 18 years to graduate from HS, etc. so you can't tell me you just found out about this last week!

)
They also know that if they DON'T need it by a certain date, I may push theirs out a little further so I can get the other time sensitive ones done. Does this work for every customer? Of course not. But the ones who like my work keep coming back (I have several customers bring me 10 or more quilts each year for the last 8 - 10 years!), so it must work for some of them. I've built my reputation on producing a quality product, so most of my customers are willing to wait for me to take my time with each quilt and do the best job I can on each of them.
It reminds me of something I read on a wall of a business once that went something like this:
It can be done good and fast, but it won't be cheap
It can be done cheap and good, but it won't be fast
It can be done fast and cheap, but it won't be good
Andi