The 4 tipped positions are head server, server, assistant server, and room host. These are the people you may have pre-paid your tips for. In addition, there is a 15% automatic tip added to any bar purchases--this includes candy, bottled water, virgin drinks, specialty coffees, etc. as well as alcohol.
The kid club counselors are not a tipped position. That means that they receive US type wages from
DCL and do not base their income on tips from guests. Any money that they receive and any gift cards that do no have their name on them must be turned over to their supervisor where it is pooled and used as funds/door prizes for a party for the department. What they LOVE and can keep are munchies...any sort of packaged goodies are appreciated. In addition, if you wish to tip a particular person, you can do it thru a gift card with their name clearly written on it. There is no pressure and no obligation to tip or present a gift to anyone in the kid areas. When DD was in these areas, I'd ask her if there was one or perhaps two people who made her time special, and would give them a gift card with their name on it as well as mentioning them in my evaluation. Your child may interact with 12 different CMs during the cruise; it's not practical to tip all 12!
Yes, the standard for tipping of the 4 main positions is that it is done on the last night--as you stated, you assess the service during the week and tip as desired on the last evening. That tip represents all the service you received during the week, fully realizing that breakfast and lunches were likely served by someone else. It is not customary to leave small tips throughout the week, although I have occasionally seen someone tip an exceptional server at lunch (and discuss it with him when the server tried to explain that it wasn't necessary).
We have very rarely had any service that was less than exceptional on a DCL cruise. They are very careful with training and educating new people as well as giving careful supervision so that things will be "Magical."
As always, tips are one of the most highly debated issues on the boards. There are the suggested tips; beyond that, go with what YOU feel is right for your situation.