Normal
Hi! To reassure you, so many firms release slots in batches so it could well mean you are one of the earliest! Worrying about things like this will also only add to the pressure you already will be putting on yourself. I used to do this a lot myself but unless you have it verified by HR it is virtually impossible to know how your chances might fare in terms of how many people they have interviewed etc, especially this early on in the cycle. Definitely stick with the slot - if there are not any earlier it is because they are at capacity for those dates or they are not interviewing until your date.