I'll have a yeast starter in the frig for a few weeks before I enhance it. I'll take the three week old starter out of the frig the night before brew day to warm to room temperature. Decant and add a half liter of 1.040 well aerated wort. Pitch at high krausen later in the afternoon.
You can make a starter with dry yeast if the extra cell count is necessary. The dry yeast needs to be first rehydrated in water containing minerals. You are creating liquid yeast by rehydrating. Don't use RO or distilled water. This will cause yeast cell loss. Add yeast nutrient to the starter wort to replace the nutrients the dry yeast had contained but used up during rehydration.