Sorry! I've written Past Simple instead Present Simple there. I meant "...that "come" is used in Present Simple instead of Present Perfect Simple... " That is, I think that when I say

If we meet when I come to Paris next year,

it means that I sort of arrive to the airport and she is there waiting for me (i.e. we meet in that way).

but when I say

If we meet when I have come to Paris next year

it signifies that I go to Paris, have been living for a while there and then we meet.

Or am I wrong and If we meet when I come to Paris next year mean that I go to Paris, have been living for a while there and then we meet?