It is an excellent cross, and the biggest of the three too, at over 3" across. Strange, since you'd think the one with 'Tamlin' as the mother would be bigger....
Flowers tend to open for me relatively early in the morning, about an hour after my lights turn on or at about 7:00 am, and stay open, depending on the species, for about two to 5 hours. Sp. Lantau Island keeps its flowers open almost all day, and the 'Tamlin' often opens late, so it's just a matter of timing. Always the best chance is usually about mid morning for me though, and if you want open flowers, the lighting needs to be strong enough to make them open.
Also, quick note, later tonight or tomorrow morning I'll be posting photos of #4, D. spatulata "white flower" x "capillaris Long Arm." A lot of similar crosses, I know, but each is interesting in its own way....