Pretty tough, the constrain 
and most better dim sum places open late in the morning or noon.
Joy Point Dim Sum 聚點
Shop No. 2A, 2 Hanoi Road, Tsim Sha Tsui
09:00 am -01:00 am
• good review and inexpensive
HK style breakfast (well, somewhat HK style “Western” tea restaurant, local likes them, but not sure Westerners would enjoy)
Australia Dairy Company 澳洲牛奶公司
G/F, 47-49 Parkes Street, Jordan
07:30 am -23:00 pm
• Signature dishes: toasts, milk tea, steamed milk (dessert), fried egg
Yee Shun Dairy Company 港澳義順牛奶公司
63 Pilkem St, Jordan
08:00 am - 00:00 am
• Signature dishes: ginger milk (sweet), double skin milk (sweet), red bean double skin milk (sweet)
If you are willing to walk to Elements (30 minutes walk), you can find
Tasty Congee & Noodle Wantun Shop 正斗粥麵專家
Shop 1080-82
1/F, Elements
1 Austin Road West
Mon-Fri 11:30 am - 11 pm
Sat - Sun 9:30 am - 11 pm
Dim Sum Square Sheung Wan 聚點坊
G/F., Fu Fai Commercial Centre,
27 Hillier Street,
Sheung Wan
Mon-Sat 10:00-22:00
Sun 08:00-22:00
• Standard of Tim Ho Wan
Sun Hing Restaurant 新興食家
Shop C, G/F,
8 Smithfield Road,
Kennedy Town,
Hong Kong
• Very famous for its liu sha bao
If you like the old style Dim Sum with trolleys, should try Lin Heung Tea House in Central or Sheung Wan (middle range), I think it is covered here in HO already. If you are a big dim sum fan, you should try at least 1 higher end dim sum meal, discussed in the thread below.
