Interesting question. My first response is a soon as possible to see if the two of you are able to connect.
But...
People to change over time and the desires inside them change too. I've become more interested in "out of the normal" things as I have aged so these are more difficult to bring up when you have been with someone for a long time.
Still it's best if you can have a sit down and talk and express the desires you have inside. Let them out slowly so as to not overwhelm your partner.
Thanks for asking this. It made me think and consider this.