Interesting...
I have lots of "delay" indeed. I do not recognise this immediate weakness you should get with mg. With me it's like this:

I do something. I feel my body saying: stop, it hurts, it's difficult, i'm getting weak. So literally every step I take costs me more energy. But I do not stop, I fight, and think: stop being such a *****. It's like fighting quicksand, but I'm still being stupid and think I can fight it. I keep going, going until one of the two things occur:

1) I've done it again, did too much, my body is broken and I am too weak to do anything (mostly it's me being in bed or hospital or something).
2) Mentally I could stop the thing I was doing, probably because I considered it done, so I rest. Now I ge a big blow of overwhelming fatigue, tiredness, weakness and feeling awful. I lay down, and have to stay there for a long time.
And days following I have more weakness.

So an example: I want to do my hair. I do it, but I feel my arms. They start to hurt, they "want to go down" and just hang there. I do not want this, I'll get angry at my arms and start fighting it. I keep going, although it starts to feel like I'm weight lifting. It's over 1 min now, I'll start sweating, ooh they get so heavy, it's like gravity is working overtime. It's like a battle between mind and body.
After almost 2 minutes I did get a ponytail, and it doesn't look like I'm retarted anymore. I did it myself! My arms can go down now.
But I'll pay for this, I can't use my arms for a while ánd overall weakness gets to me.

Hope you understand this: for me it's not like in those discriptions or MG movies. It doesn't get real paralized, or how could I fight it for a while? The real "blow" starts when I say: go and rest muscles. They do rest, but so much I can't use them. So paralizing weakness in rest... Weird eh?

Also in my worst times I do not get this "action-direct weakness-rest-better" stuff like I should. It's waking up weak, and I do not get stronger with rest, in those days it's more a surviving thing.
Weird!