I think it's really just a matter of time.
The issue from measurements of woofers I've seen is the suspension is a little too stiff at the beginning, and the resonant frequency of drivers drops afterwards.
Since the problem happens at the low-end of the speaker response, it's kind of self-healing. I mean, if you use a sub, you'll never notice the speaker breaking in, but it will, only it will take longer.
Just play your speakers as you would normally. At worst, you'll take a little longer if you high pass them.