You might have heard that in order for your integrations to be quantitative, T1 relaxation has to be complete. But how do you know it is complete? The measurement is easy. Set ds = 4 (ds: dummy scans), ns = a minimum number that you can get an OK signal (for proton, 4 is often good enough). Compare the integrations obtained with d1 = 1 s and 2 s. If they are identical, then T1 relaxation is complete at d1 = 1 s. If the latter is bigger, Repeat the comparison of the integrations obtained with d1 = 2 s and 5 s. If the latter is bigger, repeat the process until you have two d1 values which produce the same integrations. The lower of the two in your final round of comparison represents the d1 for which the T1 relaxation is complete.

This works for both the standard 1H and 13C techniques.

Please note that the above trick is not a strict measurement of T1 values. To accurately measure T1, please read this post.