I recently received Chinese Elm and Juniper tree seeds and am in the process of soaking the seeds to soften the casing. I see often that people stratify the seeds to mimic winter.

It's already early spring where I'm at, and I'm wondering if I can sow my seeds right away or if stratification is a must...?

YOu only need to do this if your aim is for a large part of the seeds to germinate.
The seeds need to experience winter for it to germinate.

Not that junper seed may take over a year to germinate.