Generally, engagement.
Maybe, maybe not. Perhaps the OP’s client took it to mean marriage and since the marriage has not yet taken place, the fee is not yet incurred. Just because you think that the term “generally” means engagement, that does not mean that the OP’s client believed it to be so. The same goes for “going rate.”
In short, if the OP has specific expectations for doing the job, then she should make those expectations clear up front. Failure to do so only invites situations such as the OP is facing now.
The Wolf