That would be correct. Lesco has a product to put down in late April and May that has dimension which helps prevent crabgrass. You can get this at Site1 landscape supplies. Do not get this at Home Depot or Lowes....the Lesco there is inferior to what you get at the landscape stores. I still get crab grass to appear sometimes, but it's easier to manage. You may have to apply this twice, In May and then late June. It will also prevent weeds. Double check with the crabgrass though....I'm pretty sure it helps prevent it.....I know it certainly helps with weeds.
Do note if it is very hot, weeds will come late July and August. I get them all the time..although not bad this year since July was cool and wet.