IGF-1's method of action has nothing to do with upregulating androgen receptors as you allude in your posting.
IGF will ideally agonise IGF-1 receptors, causing proliferation/differentiation of muscle stem cells and eventually (hopefully) some degree of muscular hyperplasia (fusion of stem cells). Hyperplasia is the creation of completely new muscle fibers as opposed to hypertrophy which is the enlagement of existing muscle fibers.
The proposition of hyperplasia due to IGF-1 is very subtle and takes many cycles at most to achieve this possibility. The subtlty lies in the creation of new immature muscle fibers that are quite underdeveloped and need time to mature and grow, not unlike the existing muscle fibers we strive to put into a state of maximal hypertrophy. With the creation of these new fibers (after some time of IGF-1 use) there will be a benefit of using AAS to speed up their maturation and rate of hypertrophy.
Other than hyperplasia with IGF, we also benefit from some other actions as well. IGF-1 agonises insulin receptors to a lesser degree than insulin, but thus it is also responsible for glucose/amino shuttling & nutrition partitioning effects which are beneficial to muscle growth in and of itself to some degree.
So, for hyperplasia the most logical reasoning is to already have some degree of hyperplasia for there to be a benefit of AAS taking action on these newly created fibers. Thus, running a first cycle of IGF with AAS concurrently will probably not create this environment as IGF needs much more time and numerous cycles. However, the nurtient partitioning and glucose shuttling effects can definitely be of benefit during cycle or stand alone.
Honestly, the question of whether to run IGF first or run AAS first or both may only be questionable IF and only if you are planning on using IGF-1 only one time and never again. This is not realistic, and if you plan on using IGF-1 you better be preparred to run it for quite a few cycles to hope for any real benefits. Thus, you can run it at any point. It will benefit you in cycle and in PCT to help hold onto gains. Personally I love it in PCT as this is a time when IGF-1 levels are quite low.
If you run a shor cycle of 4 weeks with an PH, you could follow up with IGF in PCT and then rely on the next PH cycle for stimulating the growth of the possible new fibers.
If you run a long cycle (10-12 weeks), you could ideally run IGF at the beginning of the cycle with equal time off, then in PCT.
So you see there are many ways to do this depending on the immediate benefits you want, however, the constant is that you will repeat these cycles to in in such a way that new fibers will mature with following AAS or PH cycles.
Hope this helps.
Take Care.
