Hi @benny_1,
There is no trigger for that, I'm afraid. But, you can set the entry ready one, have it sent to some URL where, using the clientlibs, the flavours for the entry are checked for their status, until they are either all ready or set to N/A, which can also happen if the source file cannot be converted to these flavours and then keep probing until all flavours are in their final state.
Alternatively, you can set all flavours as mandatory but I highly recommend you do not, since this will cause an entry to fail completely if one of the flavours cannot be created.