Banana Shallots and Onions

Hello all. A couple of questions if you don't mind as it is my first year with alliums.

Firstly, I planted some banana shallots from sets last year but nothing is peeking yet.  Does it take a while to get them going (I would have a furtle but don't have many so I don't want to disturb them)? The bulbs feel firm and are not rotted at all.

Secondly, I also planted some overwintering onion sets last year (Senshyu Yellow and Karmen) and they seem to be doing ok (so far). The problem is that in my enthusiasm last year I also ordered some spring sets (Stuttgarter Giant & Red Baron) which have now arrived and I don't have space for them. 
I can plant a few in my (small) brassica bed but would it be ok to put them in 3" pots for a few months to grow on and then maybe hoik the others out early for pickling/freezing (as I know the Senshyu will not store well) and then plonk the potted ones in? If I were to do this, what is the latest I could do this? 

All help would be greatly appreciated.

Mags 

I bought a small bag of banana shallots. I have never tried them before. They are sitting on a bed of compost in a coldframe waiting for their place to be prepared. They have not
sprouted but the ordinary shallots have.
I have also tried senshyu onions for the first time but I don't see them maturing until August and so replacing them with your main crop is not really an option.
I make a lot of use of supermarket cut flower pots (early potatoes , carrots). As a suggestion transplant the senshyu to the pots say 3 to a pot and then plant out your maincrop onions in the vacated bed. Onions develop a large root system and a 3" pot would not be big enough. Something to think about.

Glad your over wintered onions are doing well, mine are a disaster.  I'm putting some of my onion sets in a large plastic trug or two this year, planted fairly close together.  So, if you've space for a container somewhere, might be worth a think.  Having an experimental onion year 

Still nothing from my banana shallots.  A couple went mushy so I hoiked them out and the rest are still firm and have pelnty of 2cm roots but not a hint of green.  Tis very puzzling.