Pitieze for children, could do with an answer now please - is it better to give 2 5ml spoonfuls now, or one now and one in the morning?

[Saltire]

DS1 has come in , after rolling around int the grass, with very red itchy eyes and what looks like Hives on his face, and really badly on his legs.
It says on the bottle either 2 x5ml spoons daily or one in the morning and one in the evening. This is a one off, well when I say one off, what I mean is he doesn't get hayfever as a rule.
If I gave him 2 spoons now would I be able to give him another one in the morning if need be?

Should say Piriteze in title!