Learning to count can begin from day one of life. Parents can encourage their children to count by counting with them at every opportunity. Reading books provides many opportunities to count with children, if there are animals on the page then they can be counted, teaching both what animals look like and how to count. Counting can be encouraged even when walking from one room to another, measuring how many steps it is from one room to another, up the stairs, and all sorts of other places.
The next stage in counting is teaching children to count on from numbers other than one. This can be done by setting out seven blocks, getting them to count to seven, and then moving two block in front after telling them to remember that number. They will soon grasp this concept and begin to count upwards from other numbers as they develop their counting skills.
After counting from higher numbers comes skip counting. This is nothing more than the times tables, but it encourages children to learn them early, as well as grasp the idea of what they are. Printable sheets can be found online for parents to print off, and to begin with they can count through the times tables together, slowly but surely helping their children learn them. Obviously it's better to start from the two times table upwards, but there's no harm in running through them over the course of a few days and then doing it over and over again to help children learn faster.
It's important to encourage children to count on their own, which they will no doubt end up doing anyway. When children play with others they could begin counting all of the blocks they're playing with or how many of them there are, in turn teaching the other children about counting. Schools will take over teaching children to count, and they will eventually introduce a standard they should be up to if they are to keep up with the work. From here parents can start to teach what is needed for their children, and work to a standard instead of going on without knowing where to stop.
In conclusion, counting should be encouraged and taught from as early in a child's life as possible. There are many ways to do both of these, and all should be explored to keep it fresh and interesting for children to learn with.