We did a dream feed before I went to bed only if it were at least 2 hours (or three, as he got older) since the last feed, and it worked well for us between about 6 weeks and 6 months. Then, as he could easily go longer between feeds, we stopped doing it, as it wasn't changing how often he'd wake me up in the night for another feed anyway. And I started going to bed earlier- 9.30ish, so it was rarely more than 3 hours since that last feed.