As an native English speaker, I'd guarantee strange looks if I ever said "it is soon 4 o' clock." I would probably say something like "it is almost 4 o' clock" or "it will be 4 o' clock soon." It may be a common phrase in other English speaking countries, but here, the given translation would be awkward.
Not off the top of my head, unfortunately.
Btw, the bokmalsordbok gives straks as om et øyeblikk, which is also what I thought it meant, but which seems to me much closer in the future than soon.