If you are intending to take the jab, advice is to take it early, as you need to space the shots in addition to the shots you should be taking during pregnancy (influenza and TDAP). A spacing of 2 weeks is recommended for the shots so try to time it well to maximise the protection for your developing baby.
I'm 26 wks and not intending to take the jab till my baby is born. I personally think my exposure to covid is very low so I would rather wait. I'm not sure when is the best time but I think 2nd-3rd trimester is OK. you should consult your doctor first and see what he/she say.