Bigger seeds do not necessarily grow faster than smaller seeds. In many cases, the opposite is true. The germination time of a seed depends on what plant it's from, how long it's been dormant and the conditions under which it's planted.
The seeds of many common garden plants are quite small, yet if they're viable they only need between five and 20 days to germinate. Some small seeds like parsley need to be soaked before they're planted and can take up to 42 days to germinate. But one of the largest seeds of all, the coconut, can take three to six months to sprout.