This is probably more relevent to melee games

I was wondering about the timing of people cancelling actions / responses

Often the situation occurs where, i.e. an effect allows me to draw/reveal the top card of my effect, upon seeing a valuable card, my opponent then cancels the effect that allowed me to draw

When the action / response requires targets etc. - do I have to declare my full intentions up front and then wait to see if someone wants to cancel

This is highlighted with the new event cards such as Harry the Riverlands

Any Phase: Kneel any number of characters with combined printed cost 3 or lower

but I wanted to know before using Old Nan

Any Phase: Kneel Old Nan to choose a character. Until the end of the phase, that character gains or loses a Trait of your choice

Are my opponents allowed to wait and see what targets I select before deciding to cancel or not?

Initiation is always complete before cancels, resolution of effects are not. So, you must do everything involved in initiating an effect (like paying costs and choosing any cards you are told to "choose" as targets) before a cancel can be played, but once you start resolving it (by drawing cards, changing traits, etc.), it is too late to cancel.

For example, with Old Nan, you must "choose" the target who will be hit by trait manipulation before your opponent decides to cancel, but they do not get to find out which trait will be gained or lost. They have to anticipate that.

Harry the Riverlands is a bit more subtle. Since the cards knelt are not targets (no word "choose"), they do not need to be indicated as part of initiation - and your opponent doesn't get to see your entire intention before canceling.

That said, if you jump the gun and say "I kneel all your 0-cost and THAT 3-cost with Harry" without giving your opponent his chance to cancel, you tipped your own hand.

thanks Ktom - interesting to spot the difference between "choose" and no pre-requisite to choose

I'd thought that the cancel was step 2 but wasn't sure what consisted the initiation and resolution parts - do I just assume that if there is a full stop, anything afterwards is going to be part of the resolution

For Old Nan I will be wanting to turn a couple of characters into Refugees .. guess what's coming next ... so I do not want my opponent to know which trait I will choose ... given that they will be the target my opponent can assume it won't be a good trait

I certainly have to remember to stop and give my opponents a chance to cancel before I do the resolution - something I am not up to speed with yet

According to the FAQ, you intiate an effect by:

A. Determining the cost or costs (big deal for something like "Confession" - does it have an influence cost or not)

B. Check that all play restrictions are met - including that all targets you must "choose" are available

C. Apply any penaties to cost (including any modifiers to penalties), such as OOH gold penalties, to determine the total cost

D. Apply any modifiers to total cost (like cost reducers)

E. Pay the cost (kneel the requierd influence, discard the required cards, pay the required gold, etc.)

F. Event cards and cards you are marshaling leave your hand, targets you must "choose" are officially chosen, and the effect is considered to be triggered

That's everything that happens during initiation (and Step 1), regardless of how the card is actually written, and all the players get before canceling in Step 2. Everything else is part of resolution in Step 3.