It can normalize a cycle if it has been shorter. But for you, hard to guess. Yes, it can delay your period as it is the drop in progesterone that triggers that. If you are using progesterone and stop taking it later in your cycle, your period can come earlier or there might be some break-through bleeding. You will find out how all of this plays out for you. You can start taking it now. Some women take it only during the later part of their cycle to reduce cramps etc. However, that misses the benefit of having a thinner endometrium to shed. And for some, they really need to thin out the endometrium as it may be thickened from low levels of progesterone and estrogen dominance. Again, with ultra sound, my wife’s uterus was at the size of 10 weeks pregnancy. That was found during a ultrasound looking for the signs of discomfort that were presumed to be ovarian cysts. Note that progesterone also can resolve that too.
If you have a state of estrogen dominance that is contributing to your body fat or inability to reduce that, progesterone might be helpful in that regard.
Most cycling women stop when their period starts. If you do not, I guess that one could have a longer indicative period, but that is my technical guess. It might be better to get the bloody thing over with… -pardon my male humour.
One week off seems reasonable. If you get good results, you can then try two weeks off and decide what works best from there. Remember that it seems to take 2 cycles to get the result of an introduction and perhaps that long for a change. After all of my experience is second hand.
If you are noticing a drop in libido, try taking less or introducing after ovulating so your testosterone rise is not inhibited. Why would that occur? Because progesterone is a negative feedback signal for your HPOA; not at potent as estrogens. Yes your progesterone levels when you were younger may have been greater that you will achieve with progesterone cream. But the same triggers to make that progesterone also triggered E&T.
And as I pointed out, some women apply progesterone cream to their breasts to deal with breast aches/pains. To what degree that improves things over systemic delivery is not really known. But over a number of cycles, you can try it one way or another and see if there is any benefit for you.