without know what the base preperation for the lawn is I would say 'spike' it with a fork or special aerator machine to assist drainage & the 'catch 22' is do not walk on it untill it has drained. Compacting it now will render it uneven & will 'puddle' . Was the original ground the lawn is now laid on well drained to start with or is it prone to becoming overly soggy when wet?

Hello Guest, its rained and rained here and my established lawn is like a full sponge and I have been unable to cut the grass for some weeks. Presuming you made a good site for the new lawn? I would say dont worry, you just need to wait until the grass is drier and then see how it is. Do try to keep off it till the weather dries out.