Selecting first occurance in a given period of record

[Stew]

Hi,

I have a table to log sessions and user (connect_id) id's, start time
etc - see below

+---------------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+---------------+-------------+------+-----+---------+-------+
| connect_id | varchar(12) | | | | |
| session_id | varchar(32) | | | | |
| start_time | int(11) | | | 0 | |
| client_ip | varchar(16) | | | | |
+---------------+-------------+------+-----+---------+-------+

I need to create a report that will tell me, for instance, how many
sessions were started today, that's easy I know but I also need
another report that will tell me how many of those sessions were
first-time visitors.

FYI the start_time is a UNIX timestamp..

Any help would be greatly appreciated!

Cheers

Stew