Mands already answered this a few pages before. At least i guess it is the same when you just switch brands?:
As @Logan44551 and @JP1979 stated GH serum is centered around timing of test. That's not the case for IGF-1 testing.
If testing GH serum inject 10 iu's IM. Pull bloods around the 3 hour mark.
If testing IGF-1 levels. Run your desired iu's of GH for around 2 weeks and pull bloods anytime.