It's totally fine to ask questions.
One thing i’ve read a few times is about whether our LO will get on with being held or cradled by us or better being comforted in his cot. How will he know if he prefers one of another as both will result in him getting mad and also its a hard process already so i dont understand how you determine this or that wont work?
Some times you just have to guess. Something inside you (instinct) might hint to put him down, or pick him up, and you might not hear that instinct or you might hear it and still be unsure - in which case just try it. It's fine. If you put him down and try to settle in the cot you are still there with him, at no point is he going to feel abandoned or hopeless which is what causes cortisol levels to rise, he might scream in fact I'm pretty sure you can expect him to scream, but his stress level is low whilst you are there. This means that it is okay for you not to get it "right" every single time and it is okay for you to try this and that and see how it goes. As you go along you will learn what helps and what doesn't, you will learn to hear the "gut feeling" or "instinct" telling you he needs to be put down (or picked up) at the same time he will learn how to sleep in his cot and when he needs to call for you (and when he doesn't). It is team work between you and your LO. At the beginning he will just be mad with you for changing the rules, this is not how he wants it to play out but ultimately having parents who are rested and can have a proper sleep at night and a short break in the day IS in his best interests.
I think I gave you a little story in an earlier post about mine kicking and screaming, back arching etc, he needed to be held, and then without any apparent change he needed to go in his cot - and I could not explain to his Daddy what the difference was, I either had a gut feeling or I was just guessing, or just trying it to see what happened. My DS settled right away (because he was screaming to get in his cot and wanted me to let him sleep), had he not settled right away I would have tried a little in the cot and then picked him up again.
Another little story with similar result: My mum was visiting and LO was fine and happy, then became unsettled and fussing. i said he is tired, needs to go to bed. My mum wanted to hold him so did not put him to bed. He fussed more, and more, and then all out crying. I said he needs to go to bed. She refused to put him in bed telling me he is hungry (he fed every 3 hrs and was not due a feed for another 2hrs or so), then told me he wanted a dummy/paci (he had always refused a paci so this was not it) and eventually I got mad with my mum and demanded she had LO over. I took him directly to his bed, said " it's ok you can sleep now" put him down and he instantly stopped crying, smiled at me, I said "goodnight" and left the room. He nodded off right away. This is only from learning when he needs to sleep, his cues, what he needs and wants. When you have held a baby in arms for all naps you have learned what your baby needs/wants for this method, you have not yet had a chance to learn his cues for a different way of sleeping - but don't worry, you will. You really will.
That leads me on top is there a general time by something should have happened, as in his crying you pick him up and he stops after you comfort him, but what if he doesn’t stop for 5/10/15mins surely thats not practical and should be abandoned as we’re not able to comfort him that way?
There is no timing during sleep training. If you held him 15 mins and he was almost calm you would continue for another minute to 16 or 17 mins wouldn't you? It would be pointless to put him down at 15 mins not calm when you feel he is going to be calm soon. In the very early days you can expect to be with him a lot and for there not to be a great deal of sleep but it will get quicker as the days go on. I suggest you start with nap 1 of the day so you all have some practice before BT, plan who takes which shift day and night and rest whenever you can. If you can put aside non-essential house work for a few days even better, save your energy, you can catch up later.
When my DS was independently sleeping and in a suitable routine it took 3 mins to wind down, put down and leave the room. He fell asleep alone and happy. When we had difficult phases of nap dropping, moving bedrooms, teething and illness I have been with him for hours. Sleep training is going to be somewhere in between.
Please do feel free to ask more questions.