Seems quite clear to me...
If you delayed your journey by up to 3 months you have a choice. Either
1) apply using SET(M) though your application will not be processed straight away
2) apply using FLR(M), your application will be processed straight away, but you'll have to apply using SET(M) at a layer stage
If you delayed your journey by more than 3 months then you can only do the second option.