When to test??

[welshgirl21]

I haven't been ttc and have a 19 month old son but my period hasn't arrived on my 7 day break on my pill and the month before i had a month off my pill so we were careful. As of tomorrow I will be late, my cervix is very high and i am producing a lot of cm.

I tested with a first response last night which was negative, when should I test again?