IF your pieces were cut accurately and you sewed your seams accurately - I think you can just ease your pieces together. Bias edges will stretch with a lot of handling.
In this case - if were mine - (and the cutting and sewing were accurate) - I would finish assembling each block.
See if the edges are fairly straight and all the units are about the same size (within 1/8 inch or so of each other)
On a 12 inch block, 1/8 inch difference eases in so that it's almost not noticeable.
In general, though - I try to have each unit be the expected size and trim as I go. So I will square up HST units, flying geese units, triangle in a square units - I have trouble getting them "right enough" - and then square up the block. I usually don't square up the whole top, because that usually turns out "close enough" - I do measure the for the borders and have opposite sides match for length.