As long as I’m not paying a fee, I always order my next cash allocation 1 week ahead. That way if the app is down I can always get cash. If there is a significant change in the exchange rate, I’ll enter a new order the day I need it and cancel the previous once I have my cash. By debit card my transactions have all processed in a matter of minutes. Note: Your first transaction May take longer so even more reason to request a week ahead of time.
For cash pickup, I have found it difficult to get much more than 100 mil (-$500 before the craziness of the past couple weeks) except from the two main locations highlighted on this site. Given I’m living in Colegiales (b/n Palermo and belgrano) it’s not worth the time for me to go downtown to get larger amounts. It’s also worth noting that (5) $100 bills translates to ~(140) 1,000 peso bills so you will literally need a backpack to pick up any more than that.
I lucked out that the closest WU office to our 1st apartment also happened to be fairly reliable having my cash 90% of the time as long as I waited until the afternoon. I never had a line ever. Another bonus of my preferred location. I’ve been to probably 30 other WU locations across the city and I find they rarely have more than 50 mil on hand. Lastly, I will tell you the app is worthless for finding locations. The hours are wildly inaccurate and a bunch of locations have closed. Much better to use Google maps. Enjoy your time in BA!