Montreal is interviewing cases DQ'd in March currently. https://travel.state.gov/content/travel/en/us-visas/visa-information-resources/iv-wait-times.html
Adjustment of status is the safer option if you absolutely cannot risk being outside the US for long. But, someone who already has an L visa is probably not going to face issues, especially since DOS has given you that visa relatively recently. You'll have to go for a medical and biometrics before the interview so you may have to visit Canada twice depending on scheduling.
Also, can you get a Police Clearance Certificate from each country you've lived in? If not, Adjustment of Status may be your best bet.