There is no such curriculum, and no need for one. At that age, learning is driven not by cognitively remembering new information, but by the infant's CNS developing the connections necessary for new activities like walking and language. 

You do need sensory input, or the networks will not develop. There is extensive animal research on this from the mid-20th century (kittens who physiologically couldn't perceive vertical lines after being raised in a prepared cage, for example) and also evidence from disabled, neglected, or animal-raised children. But it is highly unlikely that a normal child will be sensory deprived to the point where something will not develop. 

You don't have to somehow ration sensory input, or go out of your way to increase certain modalities though - the everyday activities typically practiced with infants are sufficient. If you do more of them, or do them earlier, you will not be able to speed things up, and there is no "earliest recommended" age in the sense that you can start exposing the child to everything positive in your life right from the start - see for example Pinker's [The language instinct][1] for a good explanation of how children develop language abilities, the basic principle applies to other abilities too. 

The one thing which should never be missing from the baby's environment is a caregiver who interacts in a highly empathic way. I would suggest reading the book [The body keeps the score][2] here - that's an adult's book on overcoming psychological difficulties by somebody who led a large trauma center for years, but in part 3 ("The minds of children") he gives a very good summary of the current state of knowledge on attachment and attunement theories, and cites research on how parental behavior (mirroring, helping with emotional regulation) leads to very different outcomes many years later. Specifically, 

> the vast majority of mothers did just fine in their attunement to their infants - it does not require extraordinary talent to be what [researcher Donald Winnicot] called a "good enough mother". But [...] if a mother cannot meet her baby's impulses and needs, "the baby learns to become the mother's idea of what the baby is." 

and 

> Caregivers often don't realize that they are out of tune. [In a taped interaction, e]verything was going well until the baby pulled back and turned his head away, signaling that he needed a break. But the mother ddid not pick up on his cue, and she intensified her effort to engage him [...] Finally he started to scream, at which point the mother put him down and walked away, looking crestfallen. [...] It's easy to imagine how this kind of misattunement, repeated over and over again, can gradually lead to a chronic disconnection. 

These interaction patterns have long term effects very similar to those of children who have been abused or have lived through something terrible, like witnessing the WTC attacks. 

> Infants with seriously disrupted emotional communication patterns with their mothers at eighteen months grew up to become young adults with an unstable sense of self, self-damaging impulsivity [...], inappropriate and intense anger, and recurrent suicidal behavior. 

Since there are many families where these patterns occur - van der Kolk cites a study where 62% of children had secure attachment (the one you want), 15 percent avoidant, 9 percent anxious/ambivalent (these two are not too good, although they do grow up to be mostly functional adults), and 15 percent disorganized (the ones with the problems from the last quote) - I would say this is one area where research has shown that you should take special precautions to expose the child to the propery sensory input, specifically the proper emotional reactions from the caregiver. About everything else - music, speech, movement, smells, pathogens - is likely to be present in sufficient amounts in a normal family environment. 

One last thing which is not always present in the environment, and can be timing-sensitive, is water. There is a window for baby swimming (up to about 6 months). You can still teach a child to swim and enjoy water later though, it is just a more involved process. 


  [1]: https://books.google.de/books?id=UtFqXQosVP0C&printsec=frontcover&dq=pinker%20language%20instinct&hl=en&sa=X&ved=0ahUKEwjX1vuf1fLeAhUBDCwKHQDoCgMQ6AEIKjAA#v=onepage&q=pinker%20language%20instinct&f=false
  [2]: https://books.google.de/books?id=3Q3UAgAAQBAJ&printsec=frontcover&dq=the%20body%20keeps%20the%20score&hl=en&sa=X&ved=0ahUKEwi_n7b41PLeAhXIliwKHVt6DxQQ6AEIKjAA#v=onepage&q=the%20body%20keeps%20the%20score&f=false