Temp spike after ovulation

How long after ovulation does your temp usually spike?  I got a + opk on CD 17, so I figured I ovulated on CD 18 and would see a significant temp shift today on CD 19 - but nothing.  :/ I'm 3 cycles post miscarriage and have temped several cycles before - usually I'd see my temp spike right away after the + opk.  Wondering if a) my cycle's still off b) LH surged but but no actual ovulation c) the temp spike is just slow to start...maybe tomorrow?  Any thoughts/similar experiences?  I know I need to be patient and wait to see what my temp does tomorrow but my patience is running thin!  Thanks!