All seed packets have a sowing time printed in the instructions on the packet, what you must remember is that the packets are printed for the whole of the country and sowing times vary as to where you live.
The sowing times are mainly for the southeast and the weather is more advanced than here. February in the S.E. is the approximate equivalent of March here, late February equates to third week in March here. March equates to the beginning of April and by the time the sowing date on the packet is May then we have just about caught up.
I have found that sowing two or three weeks later than the earliest times quoted seedling have caught up with the earlier sown seeds within a month, and sometimes produce better crops.
Water seeds when sowing and transplanting then leave them to grow, unless it is very dry, and then again when the crop is coming. It is better with a watering can as the water round the roots goes where it is needed and not all over the soil.