bluetongue you really won't care about colour for long, it pales into insignificance when you've got a lovely adult dog who has well and truly settled in to the family. Brindle has always been my least favourite colour pattern and sod's law when I found a fantastic whippet breeder the whole litter was brindle. I got an amazing puppy who has thoroughly changed my mind about brindle and by the time DWhippet2 came along I wasn't even thinking about colour. Typically the most suitable puppy from that litter was exactly the sort of colour I'd have wanted first time round 
Whippets can change quite drastically in colour as premature greying is very common in the breed, all mine have it to some degree. DWhippet1 had a very striking black mask as a puppy and now, at only 6 years old, his face and front legs are almost completely white.
I was very tempted to ship a puppy to me sight unseen as I'd seen a couple online that really caught my eye but I really value meeting the breeder and the puppy.
Honestly, no remotely reputable breeder would ship you a puppy with you not even having seen it.
I'm still hoping to add whippet number two at this stage. Probably a girl. I really should wait at least 12 months before even thinking about it shouldn't I?
Speaking from experience I'd say wait until your first is at least 18 months but preferably over 2 years before adding another. My youngest two have only 12 months between them and it's been incredibly hard work at times, much more so than the previous gaps between puppies which were 18 months and 3 years. In future it'll be gaps of 2-3 years and over for me!!