If you're not sure whether to wait here's what I do:
Check the CCL exchange rate on dólar hoy. If the gap between the buy rate and Western Union rate is greater than 2-3 pesos it's likely WU will up their rate within 24 hours.
Last week when it was $208 I recommended waiting as the CCL was at $219, and about 36 hours later it went to $218.65. On Monday the CCL touched $229 for a bit and WU was at $218.65 still so it was only a matter of time.
Of course this only works if you can wait. You're also gambling short term because good economic news lowers the CCL, but long term it's value only travels in one direction, whether official, blue, or CCL.