Sinope, you can apply visa upon arrival at TIA too but the Kiosk there to apply can get really crowded. You can easily save an hour or two at the airport if you apply online and save the bar code (either print or save on your phone). Note that the bar code is only valid for 15 days so make sure to complete your online application within 15 days of arrival at TIA. I did mine only few days before my flight.
Hope this helps.