We only paid booking fee, so theoretically haven't purchase yet. I'm supposed to collect keys to my Tampines EM two weeks ago, but have written in to HDB to extend to Aug while carrying on my search for possible resale options in BB.
If both parties are willing, I don't see why we can't write in to HDB to make the swap. HDB is rather flexible as long as they don't lose $$$.
So any traders for Tampines EM, 10 min walk to MRT, 10 min walk to Tampines Giant, IKEA, Courts etc and building next blk is a NTUC supermarket. Besides, Tampines resale value is much higher than BB, but too bad, too far from parents