Im picking up an ascending wedge in the uptrend suggesting a ST correction is on the cards soon and would estimate this is likely around 3.5-3.8
Estimated this from current resistance, BvS and looking at the long term tops in the weekly chart.
Of course the SP can break through resistance at 3.5 but this is probably the most likely time for it to retrace a bit. Otherwise i would be a bit more ambitious and suggest 4.2