Counting days until threshold reached

I am not sure that I understand correctly:

Is it properly marked (in post you've said 'what is the date')

	A	B	C	D	E	F	G
1	Plant	date	rain	TEMP	200	300	400
2	A	01/01/2018	0.50	8.0
3	A	02/01/2018	2.20	2.0
4	A	03/01/2018	1.10	9.0
5	A	04/01/2018	0.25	55.0
6	A	05/01/2018	0.33	4.0
7	A	06/01/2018	2.20	15.0
8	A	07/01/2018	1.10	23.0
9	A	08/01/2018	2.20	32.0
10	A	09/01/2018	1.10	31.4
11	A	10/01/2018	2.20	34.2	X
12	A	11/01/2018	1.10	37.1
13	A	12/01/2018	0.25	39.9
14	A	13/01/2018	4.30	42.8		X
15	A	14/01/2018	2.23	45.6
16	A	15/01/2018	2.35	48.5			X
17	A	16/01/2018	2.46	51.4
18	A	17/01/2018	2.57	54.2
19	A	18/01/2018	2.68	57.1
20	A	19/01/2018	2.80	59.9
21	A	20/01/2018	2.91	62.8
22	A	21/01/2018	3.02	65.6
23	A	22/01/2018	3.13	68.5

or you want to know how many days passed (as in thread title is 'counting') from 'initial date' in particular date like:

	A	B	C	D	E	F	G
10	A	09/01/2018	1.10	31.4
11	A	10/01/2018	2.20	34.2	9
12	A	11/01/2018	1.10	37.1
13	A	12/01/2018	0.25	39.9
14	A	13/01/2018	4.30	42.8		12
15	A	14/01/2018	2.23	45.6
16	A	15/01/2018	2.35	48.5			14