Thank you for your question @gabrielamunoz. FamilySearch may not be able to give specific date on when records of a specific geographical area be available for indexing but am sure that when images of records are ready to be indexed, it will be made available for guests to help index them. Feel free to visit the link below to check frequently if a batch is ready for indexing.
I wouldn't put much trust in the Find a Project link. It doesn't have all the projects that are available for indexing and reviewing. For example, when you click on Argentina on the map, there is only one project listed. Argentina, Salta - Registro Civil, 1880-2000 (Parte D) and it is 96% indexed and 37% reviewed. The same happens when you click on the United States - there appears to be only one project and there are many, many more to work on. This needs to be corrected - especially now that we don't have Indexing Chat and that wonderful lady who always posted a listing when new projects were added and also when new collections were published.
It is much better to use Find Batches in Web Indexing to see if new projects have been added.
If your question is about when FamilySearch will add more indexed records from Argentina, I suggest subscribing to their blog. https://www.familysearch.org/info/blog-subscription
Wow! We have only 12 Spanish language indexing projects right now. That's not very many.