Not really, but be sure that you are comfortable when using the pump (expressing). It’s best not to give your baby a bottle until breastfeeding is established, as baby’s can develop a preference for the faster flow from a bottle (less work for them!).
Remember too that a breast milk may not remove milk as efficiently as a baby, so you may not remove as much milk expressing as a healthy baby with a good latch does. The amount of milk you can express isn’t an indication of your milk supply.