I reckon the opening crawl and sense of time passing will mostly come from the general Resistance vs New Order state of the galaxy stuff. I guess a limited amount of time passed between the main events of TFA and Rey setting off on her journey (plus that itself will have taken, like, some time). If you add in that thing where time passes at a different rate in magic Force places, there's room for some events to occur in the galaxy before Rey's off that world.
Unless they fudge the opening crawl, have the Rey continuation scene then some kind of Rey/Kylo training and generally time passing montage thing.