There is not a set time. It depends on other factors each year.
You get to first offset the loss against any gains you have each year so that can use more of it up. Then after applying the loss to the current gains you can take a max loss of 3,000 (1,500 MFS)per year. Turbo Tax does all the calculations for you. Just enter the prior year carryover amount.
If you transferred your prior return it should be already filled in.
The current year carryover loss from the prior year is on schedule D line 6 & 14.
On the income page The 2019 column shows the carryover to 2020 (not your current loss for 2019). Schedule D doesn't actually show the carryover amount. To find your Capital Loss Carryover amount you need to look at your return schedule D page 2. Line 16 will be your total loss and line 21 should be a max loss of 3,000. The difference between line 16 and 21 is the carryover loss for next year.
There is also a Carryover Worksheet showing the carryover from the prior year and the current amounts. Then there is also the Capital Loss Carry Forward worksheet showing the amount transferring over to next year.
In the Online version you have to save your return with all the worksheet as a pdf file to your computer to see the Capital Loss Carry Over and Carry Forward worksheets.
In the Desktop program you can go to Forms and find it in the list in the left column.
Print all forms and worksheets and view the "Carry over worksheet" line 12 for capital loss carry over.
it's not a credit it's a deduction. if you never have capital gains in the future and the law doesn't change you can divide the remaining carryover to get the number of years you will get the $3000 deduction. in the final year, you get only the remaining carryover which will likely be less than $3,000