If people are careful to follow my advice, the symptoms disappear very quickly:
The less often the nerve will be pinched, the faster it will be less inflamed and therefore less swollen, which will give more freedom of movement.
It takes 3-5 days when we do our best. Then it takes 6-12 months to heal and therefore not to be visible on an MRI.
Phase 1: Minimize nerve pinching
If, as in 95% of cases, it is due to a herniated disc, just make sure not to cause nerve compression. It is therefore necessary to avoid positions, movements and forces in lumbar flexion. 
Concretely: Keep the lower back arched.
You have to sit on chairs, not sofas (the hips should not be below the level of the knees , except for the positions where the whole body is tilted backwards: example)
Do not cross your legs, do not put them on a leg rest.
Important: use a lumbar cushion or office chair adjustment that helps to maintain good posture: An example of a lumbar cushion for chairs and cars. Caution: It must not be in memory foam because they flatten. It requires very compact and dense foam (cold foam), which does not get easily compressed.
- Do not lean forward, or carry heavy things,
- always arch your back during risky movements. 
Phase 2: Prevention
1. Once the symptoms and pain are gone, it is advisable, for prevention, to:
- Transform above mentioned measures in habits, then
- do lumbar muscles motor control exercises, to enhance the functional stability of the lower back. It takes just a few weeks, 2-3 minutes of exercises a day. 
2. It takes 3-12 months to heal and therefore not to be visible on an MRI anymore!
- Nicotine is a risk factor because it is a vasoconstrictor which, therefore, dries out the discs = they are easier to damage under load.
- Walking accelerates the healing process, prefer walking with free arms and / or a faster pace than average. However, avoid climbing hills for the first 3-6 months.
– That’s all because it’s as simple as that, so it’s surprising to hear about people who have sciatica / chronic herniated discs for years.
 This is what happens when there is flexion.
 It is difficult not to bend your back when the knees are more than 90 degrees upward.
 Do not hesitate to consult if you need advice on this level.