That's good to hear
His PR is 54 so if he come back in 2-3 months, the goal should be to be competitive for the French Open.
I think he should start on challengers, there are some on clay in South America in April (Baranquilla, Sao Paulo, Santos).
I read, on his blog message board, that the knee is doing well, he is training at full stretch now and will play two or three tournaments before RG. I've read the bit about RG in a few press reports from Uruguay and they all give the date of Monte Carlo but don't actually say that is where he will return.
He could try a comeback in DC against Columbia in double or maybe in 5th match if the score is over then.
There is a challenger in Columbia just after, I think it's a good place to comeback. I hope he will
DC is in Colombia on HC and he has said he wants to stick to clay this year. However, his brother, Martin, had surgery last week and won't be available for DC so Uruguay are going to struggle. It will be Felder, Behar and two youngsters which might tempt him to play.