When planning a new room redesign, window treatments can usually be ordered after other furnishings have been purchased. As a general rule of thumb, hard window treatments (blinds, shades, verticals, cellulars, etc) can generally be installed two to four weeks after the order is placed. Remember these are custom ordered specifically for your windows!
Fabric treatments vary in greatly in delivery time. The more elaborate the design, the longer it may take to create and manufacture. Some windows actually require the designer to make a template to insure proper installation of the finished product. It's not uncommon for a custom made window treatment design to take approximately 6 to 8 weeks from order to completion.
The next step in the process is scheduling the installation of your window treatments by a professionally trained window treatment installer. All reputable designers have installers on their staff who are truly craftspeople when it comes to insuring a beautiful, trouble free installation. Often, another week or two is needed to schedule this installation.