Morgoth and his unchaining and the rebellion of the Noldor
 

After the unchaining of Melkor after his 3 ages of inprisonment, he went about subtley sowing the seeds of discontent amongst the Noldor, this which gradually led to rebelion. I was wondering, was there any hint of how long it took Melkor after his unchaining to cause the rebelion. I found it difficult to try and put a time period for this. Did it happen over 1yr, 10yrs, 100yrs or many centuries.
Thankyou in advance

I assumed it was pretty immediate, though as time went on he became more daring, taking bigger gambles with the Elves.

Read HoME 5 (The Lost Road); there is a timeline after the narrative "The Lost Road" that reveals timeframes for the Valar in Valinor and some of the timing around the Noldorin Rebellion. It is not a final timeline, but it will provide you with some information regarding the events that led to the rebellion.

Thankyou i will do