We are given 3 different year amounts given in the Midrash Ne'elam.
- 40 years
- 210/214 years
- 408 years
As I have mentioned elsewhere (in comments, and I believe also a post), part of this section of the Zohar explicitly states that all of the dead would be resurrected by the year 5408. You can see this in the prior post. It is worded in an odd way. First it says 408 years in the 6th millenium, and it gives a phrase from the Chumash as a sign for this. Then it gives another word from another verse in the Chumash as the sign, and then makes an explicit year statement of 5408.
The 210/214 year period seems to be the years that Tsaddikim will be resurrected before the 408 years are complete.
The 40 year period that is before this can be read two ways. One is that it is 40 years for the process of Kibbutz Galuyot, another is that it is 40 years between the completion of Kibbutz Galuyot and Techiyat HaMeitim. A close reading of the text indicates that there will be 40 years of peace, after the wicked are no more and troubles have left Israel. The text refers specifically to the troubles of the end of the book of Daniel. The 40 years would therefore start at the same time as them, or immediately after they are finished.