a doubt to be cleared from nvs anna

[r radhakrishna iyer]

sri nvs anna,
namaskaram
Is it necessary brammayagyam is to be done only after maadhyamnigam?
Can it not be done after morning santhyavandhanam?
Is there any restriction on the subject?
For people, who want to do brammayagyam but not able to do maadhyaamnigam,
what to do?
please advise on this.....
A long time doubt with me with no answer.
thanks
radhakrishnan