Hello both,
My b/g twins are nearly 15 weeks old, and are sleeping well. For the last 3 weeks, most nights they have gone from 11/midnight through to 6.30/7am (also sleeping from 7.30 to 11pm). The exceptions tend to be the odd night of waking at around 3/4am, but then going back to sleep nicely after whatever measures we have used.
I couldn't face the Gina Ford book, and have instead been using Baby Secrets by Jo Tantum. The key things seem to be having a really distinctive bedtime routine (ours lasts an hour and a half, but we do do a breast feed followed by a massive formula top up), and making every hour between 7pm and 7am really boring and dark, so they know there's no point being awake. I'd really recommend the book.
The key to success is not to wake up one morning and do the whole thing, but to gradually incorporate more of the routine into your day. I started with the bedtime routine, then managed to get it at roughly the same time every night, then got the nightime feeds sorted, then daytime feeds, and finally daytime naps. It took about 6 weeks to get there, I think, but I needed help during the day to get there.
Afternoons are usually horrible, though. Yesterday was weirdly different - I lost concentration, and gave them a 50-minute breastfeed at about 2pm. They both then slept like angels for an hour and a half, had a little feed at 5pm and were really pleasant until bedtime. I'll be trying it again.