1
The next week we are going to France.
Next week we are going to France.
Use next + time expression, without the, to refer to the day/week/month/etc. immediately after now: ‘next week’, ‘next month’, ‘next year’, ‘next Sunday’.
See LAST (1)
2
In next April we are going to celebrate our anniversary.
Next April we are going to celebrate our anniversary.
On next Monday we want to visit our parents.
Next Monday we want to visit our parents.
Do not use a preposition of time before next + time expression: ‘next April’, not ‘in next April’; ‘next Monday’, not ‘on next Monday’.
3
It was 1 September, and we had to be in Paris next week.
It was 1 September, and we had to be in Paris the next week.
It was 1 September, and we had to be in Paris the following week.
The difference between next and the next depends on the reference point.
Next week normally means the week after now: ‘I’m going to Paris next week.’
Use the next + time expression, for example, ‘the next week’, ‘the next month’, ‘the next year’ or ‘the next Sunday’, when talking about past events and referring to the time after a past time, not after now.