I haven't had a period since about aug 25 ; i have a 35 day cycle. when can i take a hpt & get an accurate result? i have been spotting very little

Now: Your fertile time would have been mid september around the 13th to 17th. A test should be accurate by now, especially a blood test.

After missed period: Conception occurs within day or so of the sex. It takes about 3 weeks for the embryo to make enough HCG for a positive pregnancy test. Blood test may be done a day after a missed period. Home pregnancy tests should be done 4-5 days after the missed period. If the result is negative repeat the test in 4-5 days. Use first morning urine and follow instructions for the test carefully.