Thing is with me, I’m also on mealtime insulin, that’s why I test before every meal. I have to know my blood sugar is. If it’s over a certain number I have to account for that in my insulin dose, along with the carbs I’m going to eat. My insulin dose usually ranges 5-8 units.
My lantus is 48 units every night.

1st thing (usually right before breakfast) , before all other meals and before bed. Occasionally 2 hours after I eat

Lantus is a background insulin taken once a day and doesnt control sugars with meals it is in the background helping. Only way to control with meals is fast acting insulin n learning what items combos cause spikes.

I check mine right away in the morning and then 2 after after 1 of my meals

With Lantus I was checking right before a meal. If you check after it should be 2 hours after. Let us know how it goes.