This is too long a period for investment. The cryptocurrency market is a very young market. It is impossible to predict with confidence what will happen in three months, and even more so to say what will happen in a year.
The period of investment is not too long if you are investing your money in something like ethereum or one of the most powerful altcoins but if you are holding a coin no one knows there is a high chance that coin goes to zero in the short and long term, this is why people need to be more specific about their strategies since the term altcoins is a mixed bag, there are some really good projects but there are many projects not worth your money.