3 hr schedule
7.00: Eat
7.30: Activity
8.30: Sleep (1.5hrs) and YOU time.
10.00: Eat
10.30: Activity
11.30: Sleep (1.5hrs) and YOU time.
1.00: Eat
1.30: Activity
2.30: Sleep (1.5hrs) and YOU time.
4.00: Eat
5.00-6.00: Catnap (approx 40min) somewhere at this time to get bub to next feed/ bath
7.00: Eat, bath etc
7.30: Sleep
10/11.00: Dreamfeed.
Remember dont get caught up on the exact times. Bub will wake earlier in the morning some days for a feed, sleep shorter or longer some days. Just follow the schedule generally starting your day at the first morning feed. This could really be 6, 6.30. You will find it all tends to fall into place by the afternoon.
Basically I followed the general rule that always seems to work. A baby can stay awake as long as the last sleep. So if one time your baby only sleeps 45mins and you cant get her back down, her activity time wont last longer than 45min - watch for tired cues and put her back to bed regardless of the schedule (unless it is EAT time, feed her, keep her up for 10min then back to bed). If she sleeps 2 hrs she should last in Activity for approx 2 hrs (My bub at 3-6 months only lasts 1.5hrs up and 1.5hrs down so you can see the schedule is a general 2hr rule, in reality you will have shorter and longer naps at times).
A 3 month old shouldn't be up longer than 2hrs otherwise you may find you may have trouble getting them back to sleep because they are overtired. Read the cues rather than the clock.