How long could it usually take for dle(if at all)to develop into sle?.blood test and urine ok.biopsy soon.red patch in ears and scalp steroid working.

Can't tell: Since the presence of discoid lupus does not necessarily lead to SLE.

It usually doesn't: If you feel well, and the labs aren't worrisome with any of the specific antibodies characteristic of systemic lupus, you'll probably only have to worry about the discoid lesions which -- if that's really what it is -- can be troublesome enough. Best wishes and good luck.