I'm curious too about where to put Ultimate X but also too the now current books.
So in terms of timeline order, would it be...
Ultimate Spider-Man #1-3
The Ultimates #1
Ultimate Hawkeye #1
The Ultimates #2
Ultimate Hawkeye #2, 3, 4
The Ultimates #3, 4
Ultimate X-Men #1-6
The Ultimates #5
Ultimate Spider-Man #4, 5, 6
The Ultimates #6
So I placed what I did because Ultimate Spider-Man 1-3 went back in time a little to tell the origin of Miles Morales. The Ultimates and Ultimate Hawkeye run concurrently with Hawkeye finishing up his mission and rejoining the team in The Ultimates #3.
The events of Ultimate X-Men are essentially running at the same time with the other books and the events of Ultimate Hawkeye #4 catching up to Ultimate X-Men #6.
In The Ultimates #5 we see Nick Fury had passed along to Spider-Woman news of the appearance of a new Spider-Man. Who she then goes on to deal with that in Ultimate Spider-Man #4 and 5.
With everything up to this point now having caught up, I placed Ultimate Spider-Man #6 and The Ultimates #6 where I did because well, there is no where else to place these until we see, if anything displaces that order.