'Taster days' during retainer period

[StrawberryMartini]

Hi, am taking a 4 year old beginning 1st October. Mum has paid me retainer for September which is all written into the contract. I'm taking him one day next week and one the week after to ease him into full-time. Should this be mentioned on the contract (which obviously has already been filled out and signed)? Or can I just get on with it without the hassle of paperwork based on a verbal agreement?

I always do it through the attdance reg but not contract, but then I don't charge for 'taster' days and do max 2 hours at a time HTH

same as rubybees i just note their attendences in the reg but it is in my policys that i do taster days 3x2hrs for free